Learn Spanish (Latin America): Su papá es cubano.

In Spanish, su is very flexible and can mean his, her, their, or your (formal). You usually figure out whose dad it is based on the conversation you are having. If you need to be perfectly clear because there is no context, you could say el papá de él instead.

Why is there an accent mark on the last letter of papá?

The accent mark tells you to put the spoken stress on the final syllable. It also completely changes the meaning of the word! Without the accent, papa means potato or Pope.

Why do we use es instead of está to say is?

We use es (from the verb ser) because nationalities are considered core parts of a person's identity. You use ser for traits like where someone is from, and you use estar for temporary states or locations.

Why isn't cubano capitalized like Cuban is in English?

In Spanish, words for nationalities and languages are never capitalized unless they are the very first word of a sentence. Also, notice that it ends in -o because it describes papá, which is a masculine word. If the sentence was about his mom, it would be Su mamá es cubana.