My husband and I haveown an apartment for vacations in another country.

What you said was fine, but “own” can make this sentence sound better

It's located in hot weather and close to the beachclose to the beach, it’s very hot there.

“It’s located in hot weather” doesn’t work in English. You should just put something like “it’s very hot there” in some part of the sentence

We want to build family memories there, and its also it's location is good for both families.

This sentence structure sounds better, and the word “it’s” is possessive, not the combination of “it” and “is”

Our families will arricome at different times over there for different course of a few weeks, because we don't have enough space for everyone.

This is a bit complex, but it sounds more natural than what you wrote. I’m assuming you meant one family will spend one week there and then the next will spend another week?

I need to study English, and get better in my improvisation and pronunciation, because my husband's family don'esn’t speak Spanish.

While a family consists of multiple people, English treats it like a normal word. The verb conjugation is affected by the word being in its singular form, not the fact that you’re technically talking about multiple people. You should use “doesn’t”, not “don’t”

I have bhigh expectations about thatfor myself, because I can already have simple conversations, and also they're so flexible and understanding about my intermediate English.

“Big expectations” is a bit odd, we usually say “high expectations”. It would also sound better if you say you have these expectations for yourself

I have already had met them once before.

Also, about my family, it's a huge trip for them.

It's almost the first time that my parents will travel out of our country.

Having the word “almost” in this sentence is very confusing and contradictory

I need to get them comfortable, and explain tips to themgive them tips to travel without problems.

“Give them tips” is more natural

We want to build family memories there, and also it's location is good for both families.

it's = it is (doesn't make sense in this context)

Our families will arrive there foron different weeks, because we don't have enough space for everyone.

on different weeks = your family is getting there at different times

I need to study English, and get better in my improvisationspeaking and pronunciation, because my husband's family don't speak Spanish.

I would put "and" here and not a comma to improve flow
I personally wouldn't say "improvisation", because that is associate with a drama/theater context, but that is a minor note-- if you are referring to how well you speak without preparation, I would just say "speaking"

I have big expectations about that, because I can already have simple conversations, and also they're so flexible and understanding about my intermediate English.

I'm not sure "big expectations" is the right thing to say here, because I don't completely understand...are you excited? Nervous?

I already hadhave met them once before.

you don't need to say "already" if you are speaking about meeting them in past tense

Also about my family, it'this is a huge trip for them.my family

Just changing your sentence structure to improve flow

It's almost the first time that my parents will travel out of our country.

what do you mean by "almost"? Is it one of their first times (meaning they have left before) or is it their very first time?

I need to get them comfortable, and explain tips to themmake sure they are comfortable, and give them tips to travel without problems.

I think "make sure they are" sounds more natural than "get them", but it still makes sense either way
--> "give" tips, not explain tips

It's located in hot weather andThe weather is warm and it’s close to the beach.

What you wrote is grammatically correct, but this is how I would phrase that idea. When we talk about climate, “warm” and “hot” sort of blend together unless it’s a really hot place like a desert.

We want to build family memories there, and a. Also, it's location is good for both our families.

When used as a pronoun, “its” never has an apostrophe, but even native English speakers make that mistake a lot!

The word “both” is tricky here. At first, when you mentioned a family, I thought you meant you, your husband, and any children. I had to stop and think and realize you probably meant your relatives and his relatives. As such, I added “our” in order to prevent ambiguity or confusion. When people say “both our families,” English speakers are habituated to thinking of parents and siblings of each person!

This year we'll have our first Christmas there, and I'm so excited aboutlooking forward to it.

The use of “so” as an intensifier sounds most effective in short sentences with one clause, but others might disagree!

Our families will arrive there forduring different weeks, because we don't have enough space for everyone.

I need to study English, and get better in myat improvisation and pronunciation, because my husband's family doesn't speak Spanish.

In American English, “family” conjugates a singular noun, but in British English, “family” conjugates as a plural noun. This is another area where even English speakers don’t always agree!

I have big expectations about that, because I can already have simple conversations, and also because they're so flexible and understanding about my intermediate English.

I think this use of “so” works better because it’s used to indicate an extent rather than a strong emotion.

I’ve already had met them once before.

If you put this in the past tense, that implies that there has already been a second incidence of meeting them that you are going to mention.

Also about my family, it'This is a huge trip for themmy family, though.

It's almost the first time that my parents will travelpractically my parents’ first trip out of ourthe country.

The word “practically” isn’t a perfect fit, but the use is so common that an English speaker will know what you meant.

I need to get them comfortable, and explain tips to themprepare them and explain how to travel without problemany issues.