get your head round something

get (one's) head around (something)

To understand something that is challenging or confusing. It took a while, but I've finally gotten my head around this chapter in my calculus textbook. Wait, you two are dating now? It's going to take a little while for me to get my head around that!
See also: around, get, head

get your head round (or around) something

understand or come to terms with something. informal
See also: get, head, round, something

get your ˈhead round something

(British English, informal) understand something difficult, often with a lot of effort: The plan is so complicated — I’m still trying to get my head round it.
See also: get, head, round, something