Today is Ha holiday in my country.

Unless you write names or places later on, keep things lowercase after the first word.

iOn this day, we remind ourselves of one battle, which is called Batalla de Boyaca.

"On (insert date)" is a more common structure to use when writing about specific dates.

That battle was decisive in theColombia's independence war of Colombia.

I just made this sentence a little more succinct with my edit, but "the independence war of Colombia" also works as is. You can use either option.

Near my building apartment therebuilding is a soccer field, i. In that place, there are some people playing soccer,; others are listening to music.

Alternatively, you could have rewritten the first sentence to say, "There is a soccer field near my apartment building." The semicolon (;) I added also lets you put two independent clauses (phrases that can work as individual sentences) together without the need for capitalization.

In my city, Medellin, people are usually listening to music withat a hight level volume level, so I can heard that music sincethrough my window.

When you mention something specific (e.g. Medellin after "In my city"), be sure to add commas after both items in order to be specific. Also, I get why you wrote "[high] level volume" originally; you might have thought that "nivel de volumen" would translate as is in English. For future reference, though, be sure to write adjectives and nouns that can refer to concepts before a more specific noun (e.g. "a cat cafe").

Music is mixed with loud of people that cheer from the stands.

Also, I heard the same thing every sSunday.

If you're writing about something frequent, it's better to use the present tense. Also, never leave adjectives alone; always attach them to a noun.

Here in Medellin, people loves soccer and salsa music.

Plural noun (e.g. "people") --> singular verb form (e.g. "love")
Singular noun (e.g. "person") --> plural verb form (e.g. "loves")

Otherwise, we have a quiet afternoon; there were a few cold ones for this season.

My edit with "there were a few cold ones" is more of an assumption on my part. If this isn't what you meant to say, please let me know.

I hope it doesn't rain because inat sunset, I want gto tgo do some physicall exercise, and that could mess up my plans.

Well, that is all for today .¶
Bye.

Today is Ha holiday in my country.

iOn this day, we remindember one battle which is called Batalla de Boyaca.

Muchas veces, cuando se habla de los días, se usa "on." Por ejemplo, "On Christmas, we open presents." (En navidad, abrimos los regalos.) "I went to school on Monday." (Fui a escuela el lunes).

Near my building apartment building, there is a soccer field, in that place there are. There, some people are playing soccer, others are listening to music.

In my city, Medellin, people are usually listening to music with a hight levelon high volume so I canould heard that music sincefrom my window.

MThe music is mixed with loud of people that cheer from the stands.

Se usa "the" porque hablas de música especifica.

AI also I heard the same every sunday.

Si es algo que pasa regularmente y continúa en el presente, se usa el presente.

Here in Medellin, people loves soccer and salsa music.

Otherwise, we have a quiet afternoon, a fewbit cold for this season.

I hope it doesn't rain because inat sunset I want go to do some physicall exercise, and that could mess up my plans.

Well, that is all for today .¶
Bye.