Can someone please help me learn about servers, system administration, networking, distributed systems etc. I am a web developer and am a regular Linux user . I need some resources please ☺️☺️☺️. Also would it be a good idea to buy a raspberry pi to learn some basic stuff?

Buy a Raspberry Pi and start there :)

When I started learning about servers and developing in them I would recommend digitalocean.com. I tried to make a server out of a pi but getting a SQL database working on ARM is slow as mud.

You do pay for them to host it but you get a choice of Ubuntu, CentOS, freeBSD, or Debian and the Screenshot and autobackup feature takes a lot of the headache out of maintince IMO.

virtual machine can do too ;)