How is “not a” used?

In Punch-Drunk Love (2002), one line is: “Not a problem. Not a problem.”

Which movie is “not a” from?

The clip at the top of this page is from Punch-Drunk Love (2002).

Not a problem. Not a problem.

8 作品で登場 · 1 本目

イディオム

used for emphasis to mean'no thing or person'

1,102 本の映画に登場

not a…
used for emphasis to mean'no thing or person'
He didn't speak to me — not one word.

定義：Oxford Advanced Learner's Dictionary 第 9 版