TL;DR

One page averaged position 11.8 across 22 impressions and got zero clicks. The page appeared in search, but nobody clicked through.

what does a search impression actually tell you?

An impression says a page was shown in search results. It tells you people saw it there.

It does not tell you whether anyone visited the page.

why can impressions look better than traffic?

This page averaged position 11.8 across 22 impressions. It got zero clicks.

That is the whole story: the page appeared in search results, people saw it, and nobody clicked through.

which number mattered most for this page?

Zero clicks. When checking search performance, put clicks next to impressions so visibility and visits stay distinct.

FAQ
What is the difference between a search impression and a click?

An impression means a page was shown in search results. A click means someone clicked through to visit it.

Can a page get search impressions without clicks?

Yes. This page had 22 impressions and zero clicks, with an average position of 11.8.

Should I compare clicks with impressions?

Yes. Put clicks next to impressions when checking search performance. Impressions show the page appeared; clicks show whether anyone visited.