Learn Spanish (Latin America): Tu hermana tiene nuestras chaquetas.

In Spanish, tu without an accent mark means "your" (as in Tu hermana / "Your sister"). When you see tú with an accent mark, it means the person "you". The accent mark simply helps us tell these two words apart in writing.

Why is the word for "our" written as nuestras here?

Possessive words like "our" (nuestro) must match the gender and number of the thing being owned, not the people who own it! Since chaquetas (jackets) is feminine and plural, we must use the feminine plural form, nuestras. Even if a group of men owned them, it would still be nuestras chaquetas.

Why is the verb tiene instead of tienes?

Tiene is the "he/she/it" form of the verb tener (to have). Even though the sentence starts with Tu (your), the person who "has" the jackets is the sister (ella / she). So, "she has" is ella tiene. If you used tienes, it would mean "you have".

Do possessive words like tu and nuestras always go before the noun?

Yes! These short possessive words (mi, tu, su, nuestro) always go right before the noun they describe, exactly like they do in English.