Given a rotating shaft that rotates in its housing (on a bearing), there are cases when it may experience a force which tends to act along its length, as well as radially. This might be due to gears on the shaft which have a helical or diaganal tooth pattern. So in your example, "thrust" refers to a force applied in the direction of the length of the shaft, trying to push the bearing surface along the length of the shaft. The bearing resists this "thrust" load.
I'm not sure how clear that is - understanding this requires a some engineering knowledge as well as language knowledge, of course. I expect there are many native English speakers who would not be familiar with this technical term. :)