Quel is an adjective. Like any other adjective, it agrees in number and gender with the noun it modifies. Remember to make the liaison between quels / quelles and a following word beginning with a vowel (quels animaux).

masculine singular masculine plural feminine singular feminine plural
quel quels quelle quelles

interrogative quel
Quel is generally translated into English by ‘what’ or ‘which’. It is always followed by a noun or by the verb ‘être’ + noun.

Un petit tatou: Maman, maman, quel est le nom de ce tatou? A little armadillo: What’s the name of this armadillo?
Rita: Oh, c’est Tex, ton oncle. Rita: Oh, it’s Tex, your uncle.
Un petit tatou: Quel âge a Tex? A little armadillo: How old is Tex?
Rita: On ne sait pas. Rita: We don’t know.
Un petit tatou: Quelles sont les qualités de Tex? A little armadillo: What are Tex’s good points?
Rita: Oh, il est intelligent, débrouillard, mais aussi cynique et pessimiste. Rita: Oh, he’s intelligent, resourceful, but also cynical and pessimistic.

exclamative quel
Quel may also be used for emphasis. In this instance, quel is followed either by an adjective or a noun, and it means ‘what’ or ‘what a’. Note that there is an exclamation mark at the end of the sentence.

Tammy: Quel beau tatou! Tammy: What a handsome armadillo!
Joe-Bob: Non, quel tatou snob! Quelle belle minette! Joe-Bob: No, what a snobby armadillo! What a beautiful kitty!
Tammy: Quelle chatte méchante! Tammy: What a mean cat!
Ah, quels animaux absurdes! Ah, what absurd animals!

*Thanks to Tex’s French Grammar