"I can well imagine how you must have felt." "I can very well imagine this being true." I think you should look up the word imagine.

It doesn't make sense to me, "I can imagine well" however means you are good at imagining, you are creative.

ive only heard it that way a couple times. usually it is only 'i can imagine', to agree without true knowledge

" I can imagine" means you already know and understand what the other says and you agree to it probably due to having previously experienced the same or upon theoretical knowledge or deep understanding of a certain situation . It could mean you put yourself in the other's shoe and therefore could imagine exactly what he/she is talking about,when it is about feelings.

I think the expression "I can imagine" is used more often in conversation so I'll try to explain that here. A: It was really hot in Egypt! B: I can imagine! or B: I can imagine it being pretty hot over there! B is - agreeing to what A is saying - B has no real experience (or has never been to Egypt)