what does " get a handle on sth " mean
is it " get the hang of sth"
or "control sth " like the police control the criminal

Question

what does " get a handle on sth " mean
is it " get the hang of sth" 
or "control sth " like the police control the criminal

Answer

If sth is a abbreviation of something then you would be right, get a handle on something is to get control of it. it can mean the get hang of it depending on the context.