Can you explain a lookup table to me?

I have this project which entails everything we've learned throughout the semester. I have to create an erd , some dependencies diagrams and some sql statements based on this fictitious company's needs. All of this I can do but in the description, it says "You have decided that tiem and location look-up tables would be a good idea". Our professor told us today about this requirement and basically just told us to "look-up" what they are. That's fine but I really don't see anything that makes it clear. Sooooooooooooooooooooooooooooooooooooooo… help? HOW do I do it?