Learn Croatian: Imamo puno hrane za večeru. - We have a lot of food for dinner.

The word puno is a quantifier meaning "a lot of". In Croatian, quantifiers always force the noun that follows them into the genitive case. Because hrana is a feminine noun, its genitive form ends in -e, making it hrane.

Would the sentence change if I used mnogo instead of puno?

Not at all! Both puno and mnogo mean "a lot", and both require the genitive case. You could perfectly say Imamo mnogo hrane za večeru. In everyday spoken Croatian, however, puno is usually more common.

Since hrana is uncountable, what would happen if we used a countable noun after puno?

With uncountable nouns like hrana (food), we use the genitive singular (puno hrane). If you use a countable noun, you must use the genitive plural. For example, "a lot of apples" would be puno jabuka.

Why does the word večera change to večeru at the end of the sentence?