Psychology Descriptive statistics exam

I have research methods exam for psychology next week . open book exam.
even though it is open book, i simply just dont understand statistics , is there any advice out there on how to revise for this exam next week.

I've been told past papers but that doesnt help if you dont understand anything in the first place.
All my previous lecture slide have been taken down and even those are not very helpful.

please any help out there, or im willling to pay for tutor