To get your head around something is to manage to understand something difficult. Get your head around the new system.
It suggests the difficulty is size rather than complexity, since the head has to go round it. It is informal and takes time rather than cleverness.
1phraseget your head aroundTo manage to understand something difficult.
“It takes a fortnight to get your head around the filing here.”
get your head around is a phrase.
Practised in Thinking & Memory