Learn French: L'éléphant boit beaucoup d'eau. - The elephant drinks a lot of water.

After expressions of quantity like beaucoup, un peu, or trop, French uses the preposition de (or d' before a vowel) without the definite article (le, la, or l'). Therefore, it is always beaucoup d'eau, never beaucoup de l'eau.

What is the infinitive of boit, and how does it conjugate in the plural?

The infinitive is boire (to drink). It is an irregular verb that B1 learners should watch out for. While the singular forms use the oi sound (such as il boit), the plural forms change the stem, giving us nous buvons, vous buvez, and ils boivent.

Since we see l'éléphant, how do we know if éléphant is masculine or feminine?

The l' does not tell us the gender because both le and la shrink to l' before a vowel. You just have to memorize that éléphant is masculine (un éléphant). If it were a female elephant, you would specify by saying une éléphante.