a handle on
1. A good physical hold on something. Make sure you've got a handle on your end of the couch before we try to lift it.
2. A newfound understanding of a topic or concept. Once I got a handle on how to operate the new system, I found that it made my job much easier.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
*a handle on something
Fig. a means of understanding something; an aid to understanding something. (*Typically: get ~ have ~ give someone ~.) Let me try to get a handle on this. Now that I have a handle on the concept, I can begin to understand it.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.