To catch up is used to describe the process of bringing yourself up-to-date with some news, some information or, perhaps work.
For example, at the weekend I met my mate who I’ve not seen for a few months and we spent the afternoon catching up on our news, i.e. we spent the afternoon chatting about what we’ve been doing over the recent past. In addition, on Sunday afternoon I caught up with a lot of outstanding paperwork and house chores. BORING, BORING, BORING.
However, be careful, this phrasal verb can mean different things in different contexts. Do you want to know what they are? Well check out some definitions here.