Questions & Answers about Da li si slobodna danas?
Da li is a very common way to form a yes/no question in Serbian. It does not have a neat word-for-word English equivalent; it functions more like a question marker. In a sentence like this, it signals that the speaker is asking for confirmation rather than giving a statement.
A very common alternative is Jesi li slobodna danas?
Si is the 2nd person singular present tense form of biti (to be), in its short/clitic form.
So here it corresponds to are in Are you free today?
Compare:
- ja sam = I am
- ti si = you are
- on/ona je = he/she is
Serbian often drops subject pronouns when they are already clear from the verb form. Since si already tells you the sentence is about you singular, the pronoun ti is not necessary.
You could say Da li si ti slobodna danas?, but that adds emphasis, something like Are you free today?