Motivation and presentation not explained in the paper My conference paper got conditionally accepted, but one of the remarks of the reviewer was: "The presentation and motivation are not explained." I'm not sure what to think about this. English is not my native language, so I'm not quite following what does this means. 

What doeas "presentation" in the paper means? I was at the conference, and I have presented my work, but I guess that definitelly doesn't have anything to do with this review. 

And about motivation, I'm not quite following how motivation is not explained? Can someone point to a few examples that explain this issue?

I hope I haven't done anything wrong quoting one sentece from the review. Also, I'm really sorry if it is something that happens quite often. Oh, I forgot to say that I'am a mathematician.:)
I agree with @gnometorule.  It looks like the reviewer wrote a sloppy comment.  I imagine the reviewer meant, "The presentation needs improvement, and the motivation should be explained better."  Presentation means how you present your ideas.  I suppose the reviewer felt that the ideas could be presented more clearly.  Motivation makes the reader care about your contribution.

Hopefully the reviewer also made some specific comments that will guide your revision process.