As far as I know, Italki points indicate how active you are on the italki site. The more you do (classes, questions, notebook, ect) the more points you get and the more points you get, the more active you are and the more active you are, the more people may wish to follow you.

This is what I saw when I clicked it: "italki Points is an experimental feature. We are testing some ideas about giving users points for behaviors that make the italki community a friendlier and more useful place to learn a language." and I'm pretty sure that it's the points you get from answering question and correcting notebook entries, etc. :)