Everybody thinks that in Spain all peopleveryone mtakes a nap after lunch, every days of the year.

I live in Catalonia, and I don't know nobody anyone who (does/practices) "la siesta" induring the weekdays.

BuHowever, it is possible that some people ido it on some days on, like during holidays or the weekend, they doing.

We try to not start sentences with "but" in written English, although we often do it in spoken English.

In others spots mothat are hotter, where is not possible gto out fromleave home during the day in the summer while the sun is stronger, traditionally they do this short sleeit is common to take a nap.

The "siesta" should last around thirty minutes to 1(an/one) hour.

If your nap lasts longer time,, it is possible that later at night, you will havexperience problems for shut-eye to sleeping.

Everybody thinks that in Spain all people meveryone in Spain takes a nap after lunch, every days of the year.

I live in Catalonia and I don't know noanybody who does "la siesta" ion weekdays.

or

I live in Catalonia and I don't know anybody who does "la siesta" during the weekdays.

BuIt is possible, however, that some people inap on some days onduring holidays or weekend, they doings.

In others spots mowhich are hotter, where it's not possible go out fromto leave home during the day in summer while the sun is stronger, traditionally they do this short sleep.

The "siesta" should last around thirty minutes to 1one hour.

If your nap lasts longer time, it's possible that, later that night, you will have problems for shut-eye to sleeping.

or

If your nap lasts longer, it's possible that, later that night, you will have problems getting some shut-eye.

Everybody think that in Spain all people mak(have a) nap after lunch, every days of/all year.

I live in Catalonia and I don't know nobody who doehas "la siesta" induring the weekdays.

But is it possible that some people ion some days onf the holidays or the weekend, they doing. are doing it/having it?

This is a rhetorical question you need a ? At the end

In others spots more hot hotter areas, where it is not possible to go out from home during the day in summer while the sun is stronger, traditionally they do this short sleep, traditionally people nap/people nap more frequently.

If your nap lasts longer time, it is possible that later at night, you will have problems for shut-eye to sleeping.

Everybody thinks that in Spain all people meveryone in Spain takes a nap after lunch, every days of the year.

The sentence sounds more natural if you make "everyone in Spain" the subject.
Also, having "everybody" and "everyone" right next to each other sounds a little repetitive in writing. You could replace "everybody" with "most people."
Finally, you "take a nap" in English!

I live in Catalonia and I don't know noanybody who dotakes "la siesta" ion weekdays.

"I don't know nobody" would make sense to native English speakers, but it sounds very informal and dialectical.
"To do a siesta" doesn't sound wrong to me, but since it's the same concept as a nap it's better to use the verb "take."

But it is possible that some people in some daystake one occasionally on holidays or the weekend, they doing.

To sound natural here you have to put the action (taking a siesta) after the subject (some people).
You also have to name what you're talking about (you can't just mention "doing" something). Here you can just referring to taking a siesta as "taking one" because the context of your writing is clear.
I changed "some days" to "occasionally." This sounds better because it avoids the repetition of "days" in "some days" and "holidays."

In others spots more hot, where iswhere it's hotter and not possible gto out fromleave home in summer, traditionally they do thistake a short sleenap, while the sun is stronger.

You can include the information of "hotter" after the relative pronoun "where" since it also refers to the spots.
In English you "leave" home. "Go out" refers to leaving with plans to do something, usually at night (watching a movie, partying, etc).

If your nap lasts longer time,[than that], it is possible that later at night, you will have problems for shut-eye to sleeping.

"Shut-eye" is an informal way to refer to sleep, and you can't really combine it with other words.
You could say "you won't get any shut-eye," but then you'll kind of sound like a cowboy! 🤠