1. unable to understand or accept something
I can't get my head around why something happened
To 'get your head around' something means to finally understand or comprehend something that is difficult or challenging. It can also be used to talk about accepting something that is contrary to your ordinary beliefs. If you 'can't get your head around' something it means it is difficult to accept or impossible to understand. This is a casual expression that can be used in social and professional contexts.