What does presto mean in Spanish?

Depending on context Presto (a form of the verb Prestar) means Lend, however it can be taken to mean borrow.

However it really means "to lend". In Spanish when you ask to borrow something you are really asking some one to lend you that thing.

Te lo presto. - I will lend it to you

¿Me lo presta? - Will you lend it to me? (Can I borrow that?)

Presto can also mean exactly the same thing as English when referring to a musical notation, i.e. quickly (adverb).

And as 'presto/a' (adjective; male/female) - quick, ready, prepared