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