You can read it as "pull on gear". In "free climbing" pieces of gear are slotted inside cracks and the rope is clipped to them for safety. If you grab the gear and use it because you can't climb the natural face it doesn't count as "free-ing the route". Many routes have sections where this is mandatory or very common. There might be a great moderate climb with one small stretch that is significantly harder, so people pull on their gear through that bit and enjoy the rest.

There is also great pride in being the first one to "free a route", free climbing a route where all previous parties have used gear (also called aid climbing).

Full-on aid climbing generally involves hanging a ladder from gear, stepping up on the highest rung, and placing another piece of gear and a higher ladder. This can actually be incredibly physical and incredibly mentally taxing since the gear used might be a tiny hook hanging off a dime edge, or a postage-stamp sized piton hammered into a seam.

Hope that helps!