How do you manage your income/savings?

I am unfortunately absolutely clueless regarding finances, interest, banking, investing…all things money related.

For the last 6 years I've received my salary and it's gone straight into my (sole) bank account and just sat there until I withdraw some to use.

My main questions are:

What should I be doing with my savings/ income in order to use them effectively/earn money through them?

Should I be splitting my savings across multiple banks? Is there a reason not to put all my savings into just one?

Any advice would be greatly appreciated, thanks.