How is “get a handle on” used?

In Memento (2000), one line is: “But he's acting funny. He can't get a handle on what's going on.”

Which movie is “get a handle on” from?

The clip at the top of this page is from Memento (2000).

But he's acting funny. He can't get a handle on what's going on.

6 作品で登場 · 1 本目

to understand or know about sb / sth, especially so that you can deal with it or them later

くだけた · 5 本の映画に登場イディオムを再生

オックスフォード映画の 100%
to understand or know about sb / sth, especially so that you can deal with it or them later
But he's acting funny. He can't get a handle on what's going on.
I'm spazzing out in there, I know, but something fucking weird like Twilight Zone shit is going on here, and I'm trying to get a handle on it, okay?

定義：Oxford Advanced Learner's Dictionary 第 9 版