French language Q&A Forum

What is the real difference between "de plus" and "en plus"?  In this writing exercise, the English word "plus" is translated as "en plus,"  "in addition" is translated as "de plus," and "besides" is also "de plus."

How would "what's that (used) for" and "what does that mean" look in french (considering the three ways of asking question(s))?

1) À quoi ça sert? Que veut dire ça?

2) Ça sert à quoi? Ça veut dire quoi, ça?

3) Qu'est-ce que ça sert? Qu'est-ce que ça veut dire?

I have seen that the verb « apprendre » can mean both to learn and to teach in French. And I also know that « enseigner » can sometimes mean to teach (but in a narrower sense, and it can never mean to learn). My question is : Can one say in this exercise «  je lui ENSEIGNERAI à être indépendante et forte » or is this just a wrong usage of this verb?