Doing shit, basically. Reading and discussing theory is cool and all, but joining strikes and helping on food drives, etc. is where the rubber really hits the road.
Doing things, or more exactly the way things are done (but it's used to refer to carrying out material actions in that way as well). It's also roughly synonymous to one of the meanings of "practice," as in "established practices" or "best practices," which are more or less what "praxis" means.
tl;dr: it can be either a method for doing material things or the act of carrying out such a method, depending on context.
Praxis is inflammation of the lining of the rectum. It can cause rectal pain, diarrhea, bleeding and discharge, as well as the continuous feeling that you need to have a bowel movement. 1