Learn Spanish (Spain): ¿Qué estudia la chica joven?

estudia is the "he/she/it" form of the regular verb estudiar (to study). Since the subject is la chica (the girl), we drop the -ar ending and add -a.

Why is the verb placed before the subject (estudia la chica)?

In Spanish questions, the verb usually comes right after the question word (like Qué). This means the subject (la chica) often comes after the verb. Also, notice there is no translation for the English helper word "does"!

Why is it la chica joven and not la joven chica?

In Spanish, descriptive words (adjectives) almost always come after the noun they are describing. So instead of "the young girl", the word order is "the girl young" (la chica joven).

Since chica is feminine, why doesn't joven change to match it (like "jovena")?

Adjectives that end in a consonant, like joven, are neutral and stay the same for both masculine and feminine nouns. It is el chico joven (the young boy) and la chica joven (the young girl).