1. and *a hold on somethingLit. a good grasp on something. (*Typically: get ~ have ~ give someone ~.) Try to get a grip on the ropes and pull yourself up.You should get a hold on the knob and turn it firmly.
2.Fig. a thorough knowledge of some topic. (*Typically: get ~ have ~ give someone ~.) I need to have a grip on the basics of accounting.Try to get a hold on all the facts first.