“DEPENDS OF” NO ES CORRECTO
One of the most difficult things in the English language are collocations. In this particular case, we are talking about collocations between a verb and a preposition which can be tricky (dificil).
Spanish speakers love to use the contruction: "depend of" which I think comes mainly from the subconscious connection with the phrase "depende de" in Spanish. The correct version in English is "to depend on". For example: "It depends on how many clients we have."
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 15 años de experiencia enseñando inglés a españoles.