make (someone's) head spin
to make someone confused or overwhelmed, to make someone dizzy
The information that I had to learn in the accounting course made my head spin.
Tips to get ready for Foreign Trip
Decide beforehand how you will get cash. If you want a little local currency to get you through the first day or so convert your money at a major hometown bank. Airport converting counters carry fees and can be confusing if you do not speak the language. A leftover coin or two is a fun memento, but $40 in leftover dinar? Not so much.