My site is compromised

There are some suspicious html code as below –

[ Redacted, do not post that in these forums. ]

(space is intentionally inserted for prevent execution)

I am not into coding. Where will I find this code? Can I try removing?
I have a backup of before this.
Will that help?

from html, it may appear in your admin panel theme customize widget/secondary footer, something like that

Please remain calm and carefully follow this guide.

When you’re done, you may want to implement some (if not all) of the recommended security measures.