"This is what he is doing."
Translation:C'est ce qu'il fait.
to turn que into "what" you need a demonstrative (I think....) article. Like Est-ce que - notice the ce que. C'est qu'il fait would roughly translate to This that he is doing which is nonsensical.
But as I always end my posts. I know nothing about this language and am only spitting out what I think to be true, so don't take my word for it
Okay, "ce qui" (subject) and "ce que" (object) both mean "that which" similar to "lo que" in Spanish. We should probably learn these as single words--not think of "ce que" as two words at all.
Or, a different way to think of it, use plain "que" for "what" when the phrase modifies a noun. E.g. "Le garçon que boit" "the boy who is drinking" But if the phrase has to function as a subject or object, then you need "ce que" (as though you needed to give que a fake noun to modify.) So I think "Je sais ce qu'il boit" would be "I know what he is drinking." (Perhaps a native speaker can confirm?)
"Schaum's Outline of French Grammar: Fifth Edition" (Crocker, M; 2009; p 274)
Ce que is the French relative indefinite direct object pronoun meaning "what." Think of it as a unit. So you have: "This is (c'est) what (ce que) he is doing (il fait)." There are lots of ways to say "what" in French, but this is the way you have to say it when joining a main and relative clause that deals with something indefinite.
Sorry you're feeling that way, but keep it up. This sentence is pretty straightforward grammatically once you get past all the contractions, since it's in the same order as the English.
C'est = This is
ce qu' (ce que) = what
il fait = he is doing
You probably get the first and last of those. The strangest part is probably «ce que» for "what," since there are a lot of ways to say "what" in French, depending on the role in the sentence. When you need a "what" to connect two clauses and it's an object, use "ce que." For example:
Dis-moi ce que tu veux. = Tell me what you want.
Je ne sais pas ce qu'elle a dit. = I don't know what she said.
Examples from: http://french.about.com/od/mistakes/a/what.htm