[David L.]

She was not understanding.
I was calling.


I will post my reply here so everyone can see and maybe add their comments, and also send a PM to the person who posted this question.
No, not on their own, out of some context in a longer sentence. But look at these sentences:

He was trying his best to explain Einstein's Theory of General Relativity, but it was clear from the look on her face that she was not understanding very much of it.

I tried to explain I was late for work because one of the children was ill, but she was not very understanding. (= she was not empathetic, by imagining herself in the same position of having to take care of a sick child, and so being sympathetic towards her and appreciating that in such a circumstances, one might indeed be late for work. Instead, the boss ("she") was cold, and took the line, employees should be at work on time.)

I was calling and calling. Where were you?
I was calling to see if you would like to come to dinner next Saturday.

Oh dear. This person is unregistered so that I can't send them a PM! Hopefully, they will come back to the forum when they are able, to check to see what replies they have had.