Hello, my name is Priscilla.

This is very nitpicky but I think adding a comma is more natural!

I was born in Germany on 31aAugust 31st, 2007.

My hobbies are listening to music, ywatching YoutTube and reading.

I do that in my free time and I havlike to play games on my phone.

My favourite school fasubject is math.

I am fifteen years old.

My favoutrite music is pop.

"My favourite (kind of) music is pop." is also good

My hobbies are listening to music, watching youtube videos and read.ing

I do that during my freetime and I have to play games on my phone.

My favourite school faubject is math.

I am fifteen years old.

My favoutrite genre of music is pop.

I was born in Germany on 31auguAugust 31st 2007.

Month then day then year (If this is English in the USA) August 31, 2007 would also be correct.

My hobbies are listening to music, youtubeing and reading.

If listening is with an ing, then youtubing and reading should be as well. Youtubing is kind of a made up word, but everyone will know what you mean since you tube is so popular. Kind of like slang.

I do that in my free time and I have toI play games on my phone.

Not sure if you are saying you do your hobbies in your free time or you play games on your phone. I made the correction as if you play games on your phone in your free time.

My favourite food is candy and my favourite colors are purple, blue and pink.

Spelling correction

My favourite school fact is math.

favorite

My favoutrite music is pop.

I was born in Germany on 31august 31, 2007.

In American English, the date comes after the month. The comma afterwards is used to separate the date from the year.

When I was three years old, my family moved to Vienna.

Commas are important to contain a phrase or clause and how it modifies the subject.

My hobbies are listening to music, watching youtube, and reading.

This sentence had mismatching objects in the conjunction.

Objects in a conjunction should be the same type. All gerunds, all objects, all clauses, etc.

I do thatem in my free time, and I have to play games on my phone.

The sentence refers to a collection of objects. "That" typically refers to a single object. "These/those" is the plural form, but also accounts for distance of the object.

Since distance is not a concern, "them"is more appropriate.

My favourite school fasubject is math.

"fact" is an idea or statement. Subject or topic would be appropriate.

I am fifteen years old.

My favoutrite music genre is pop.

The word "music" is used vaguely here and doesn't make sense if you used it alone.

In English, music can be heard, read, or written and is used in many different contexts. An additional word is needed to clarify the meaning of the sentence.

I was born in Germany on 31athe 31st of August, 2007.

My hobbies are listening to music, watching youtube and reading.

I do that in my free time, and I have talso play games on my phone.

My favourite school fasubject is math.

I am fifteen years old.