You’re pretty/cute/beautiful is correct. “Your pretty/cute/beautiful” is incorrect and you should not use this phrase in English.
You’re pretty/cute/beautiful is a contraction of “you are pretty/cute/beautiful”
“Your pretty/cute/beautiful” is a very common mistake in English because “your” and “you’re” sound very similar and have similar meanings.
“Your” is the possessive pronoun of you. This means that we use “your” when something belongs to “you”.
That is your house(you own the house).
“You’re” is the same as “you are”. It is a contraction which means we put two words together often when we are speaking.
The phrase “to be pretty/cute/beautiful” needs the verb “to be” to function and for that reason, the correct way is “you’re pretty/cute/beautiful”.
You’re pretty/cute/beautiful example sentences
You see a nice boy/girl and you want to text them.
A man came up to me and said” You’re pretty”!