The CPU is the brain of the computer. There’s a lot that goes into what makes a CPU good, but essentially (as with most things in a computer), the bigger the number the better. There are two major CPU manufacturers right now, AMD and Intel. AMD is still kind of new, but you’re starting to see them in a lot of new laptops. Usually you want to look for 3’s, 5’s, and 7’s. If it says Celeron, Pentium, or Athelon—don’t get it.
RAM stands for Random Accessed Memory, and it (along with your CPU) is what allows you to run apps on your computer. Neither Windows nor MacOS is designed to run on less than 8gb of RAM, so if you see a budget PC with 4gb, you should stay away.
For your storage, you want to look for something that has an SSD, not an HD or an HDD. The latter are mechanical drives that have to actually spin a disk to store something. It’s not fast, and this is a HUGE factor in computer speed. I would shoot for at least a 256gb SSD.
If you’re getting a Chromebook, the specs are going to be lower because ChromeOS is a lighter-weight operating system.