How to know which Linux version you are running

Easy peasy!

Run the following command in a Terminal:

lsb_release -a

You should see something similar to this:

pi@raspberrypi:~ $ lsb_release -a
No LSB modules are available.
Distributor ID: Raspbian
Description: Raspbian GNU/Linux 10 (buster)
Release: 10
Codename: buster