Learn French: Elles jouent du violon depuis l'âge de cinq ans. - They fem. have been playing the violin since the age of five.

In French, if an action started in the past and is still happening right now, you use the present tense with depuis. Because they started playing at age five and are still playing today, we just use the present tense jouent.

Does depuis mean "since" or "for"?

It can mean both! You use depuis to say when an action started ("since", as in depuis l'âge de cinq ans) or to say how long it has been going on ("for", as in depuis cinq ans which means "for five years"). In this sentence, it refers to a starting point, so it translates to "since".

Why does the sentence use du violon instead of just le violon?

When you talk about playing a musical instrument in French, you always use the verb jouer followed by the preposition de. Because violon is a masculine noun, de and le combine to make du. Note that if they were playing a sport or a game, you would use jouer à instead!

Do I really need to say ans at the end? Could I just say depuis l'âge de cinq?