wrap one's mind around

Erica and Amaury from frenchpod.com discussing a great variery of cheeses you can buy in France.

Erica: How many types of cheese are there in France?
Amaury: There are in between 350 and 400 different types of cheeses, can you imagine?
Erica: No, it is hard to wrap your mind around that number.

I think it's a nice expression you can use meaning to find a way to understand or accept something.