You learn a lot about the brain and behaviour of humans and animals and you'll have to learn how to design and carry out the experiments to test your hypothesis as well as adhere to codes and ethics as you're dealing with living organisms.
Section C of each of your Psychology exams will have you create hypothesis(es) and identify variables and discuss depending on the scenario OR an extended response (not necessarily research methods)
If I remember correctly, in the unit of Sleep, you need to know a lot about research methods...EEG, EMG, EOG (don't worry they aren't as hard as they seem)
If you wanna do well in Psychology, learn your research methods really well! I know it's dry, it's monotonous, bland what have you... BUT it's really important! So get your head around it early!