It's a speedy, short-term memory that holds data that programs need quickly and gets instantly deleted when the program is closed or the computer is powered off. All computers need some amount, as it's essential for the boot up process and thus the computer won't power on without it.
This is RAM I received as part of a bundle that came with the motherboard and CPU. It's 32GB DDR5 running at 4800Mkz. It not soupy, but gets the job done!
There isn't much to talk about here, so here's a fun gif of a spinning RAM stick:
