My fFavorite sSeason

Capitalization

In my country, the summer is a little bit hot, W and the winter is a very cold season.

Fixed grammar

I think it is understandablyobvious that I like Ssummer.

Summer is not a proper noun and added a more natural word

In summer, you don't have to wear a lot of clothes and you don't have to go to school in Ssnow Sstorms.

Unnecessary capitalization. And grammar mistakes

But WHowever, winter is beautiful too.

Unnecessary capitalization, and in grammatically correct writing it is not good to start sentences with "but".

For me, summer is a time when I can develop because all summer we have holidays all summer long.

I am not sure what you meant by develop

You don't needhave to sit in school in the heat when our schools haven'tthe heat at school when our schools don't have any air conditioners.

More natural

Nevertheless, Summer has minus for mesome disadvantages.

Minus isn't used when talking about pros/cons or advantages/disadvantages.

It has a lot of insects and sometimes it's too hot .

In my country, summer is a little bit hot, W and winter is a very cold season.

'and' is used to make it a full sentence

I think it is understandablye that I like Ssummer.

OR 'Understandably, I like summer'

In summer you don't have to wear a lot of clothes andor go to school in Sa snow Sstorm.

'or' is used as they are to things that don't have to happen at the same time

But Wwinter is beautiful too.

This is fine but its sound more natural if 'but' doesn't start a sentence. Either add it to the previous sentence or don't use 'but' --> 'Winter is beautiful too'

For me, summer is the time when I can develop because all summer we have holidays all summer.

'all summer' is additional information so it sounds more natural if it is after the main information

You don't need to sit in school in the heat when our schools haven't got air conditioners.

Nevertheless, Ssummer has minusome drawbacks for me.

Sounds more natural and uses 'some' as you list more that one reason - would be 'a drawback' if you list only one thing

My fFavorite sSeason

Important words in title need a capital letter.

In my country summer is a little bit hot,. Winter is a very cold season.

Joining two sentences with a comma is called a comma splice and it not good grammar.
Needs to be:
In my country summer is a little bit hot. Winter is a very cold season.
or:
In my country summer is a little bit hot; Winter is a very cold season.

I think it is understandablye that I like Ssummer.

"summer" is not written with a capital letter.
understandable not understandably. Need the adjective not an adverb.

In summer you don't have to wear a lot of clothes and go to school in Sa snow Sstorm.

"snow storm" does not start with capital letters.
you could say "... clothes or go to ..."

But Wwinter is beautiful too.

"winter" does not start with a capital letter.

For me, summer is the time when I can develop myself because all summer we have holidays all summer.

Think "we have holidays all summer" sounds better.

You don't need to sit in school in the heat when our schools haven'tithout air conditionersing.

Have rephrased the end of the sentence.

Nevertheless, Ssummer has minuses for me.

"summer" not capitalised. Summer has more than one minus so use plural form "minuses".