Can you help me with English plz?

If you grill your meat, you don't need to bother with removing the grease, because it will have moved off the meat already. (If you cook your meat any other way you will have to remove the fat or grease from it yourself.)

grilling means to cook on a grill, a lattice of metal bars, usually. The open space allows the grease to drop (rather than pan frying where the grease accumulates). Drain away means simply to pour out the liquid. Well, if the liquid already dropped on its own, you won't have anything to drain.

I personally do not usually drain (recover) the grease while cooking, but do so only when done.

And it isn't exactly true that you do not have to deal with the grease if you grill. It still goes somewhere, usually some sort of grease trap. Otherwise, you risk a very serious grease fire.

But as a simple idea, you don't have to deal with the grease while cooking if you grill, because it drips (drains) away on its own. Doesn't get trapped on the cooking surface.