Learn Croatian: Zanima me da li ste spremni.

In English, we use 'if' for both conditions ('If it rains...') and questions ('I wonder if...'). In Croatian, ako is strictly for conditions. When you have a yes/no indirect question like this one, you must use da li (which acts like 'whether').

Why does Zanima me mean 'I wonder'? Doesn't it mean 'It interests me'?

Yes, it literally translates to 'It interests me.' Croatian doesn't have a single common verb that perfectly matches the English 'to wonder.' Instead, using Zanima me is the most natural way to express 'I am curious' or 'I wonder' before an indirect question.

Why is the adjective spremni in the plural form?

Because it follows ste, which is the plural 'you.' In Croatian, the adjective must agree with the pronoun. You use this plural form (spremni) whether you are talking to a group of people or speaking formally to just one person.

Can I change the word order and say da li spremni ste?

No, because ste is a clitic (a short word that has no accent of its own). Clitics strictly belong in the second position of their clause. Since da li counts as the first position of the indirect question, ste must come immediately after it.