Is it common to call some kind of figures "visual"?

This post call this figure

"LotArea visual".

Usually, I see people call this a figure or a plot. "Figure" is perfectly acceptable, since almost all of textbooks call it "Figure".

The question is: is it common to call this kind of figures "visual"?

I think you're overreading the source here.

The article is about using visual interpretations of data.

The graph shown would be referred to as a figure. They may have titled the graphic with the word visual as a reference to the subject.

Yes, you could call a figure in a text a visual, no one could call that incorrect. But, figure is the more common term.