Learn Croatian: Hvala lijepa! Nema problema. - Thank you very much! No problem.

In Croatian, hvala is actually a feminine noun meaning "thanks". To say "thank you very much", Croatians often use the adjective lijepa (beautiful) in its feminine form to match it. You are literally saying "beautiful thanks"!

Why does the phrase use nema (doesn't have) instead of a word for "is not"?

The verb nemati (to not have) is frequently used to mean "there is no" or "there are no". So nema here translates perfectly to "there is no".

Why does problema end in "-a" if the dictionary word is problem?

Whenever you use nema to say "there is no", the noun that follows must take the genitive case. Since problem is a masculine noun, its genitive ending is -a, making it problema.

Can I just say hvala on its own, or do I always need to add lijepa?

You can absolutely just say hvala! Adding lijepa just makes it stronger and more polite, similar to saying "thank you very much" instead of just "thanks". Another common way to express this is hvala puno.