If your linux OS supports secure boot then it does help improve security.

The differing opinions on it are often because it can cause issues in some set ups and in a default set up its only a marginal security gain.

It will add a layer of security at boot by preventing 3rd party unauthenticated processes / software from running and creates a secure boot chain from your BIOS up to the OS. But the default set up also means other authenticated OSes like Windows can be run, so its not as secure as it could be.

To really secure it you could create your own keys and then only your OS could boot. But as a linux newbie thats likely way more than you need and there are risks if you fuck up, to the point of accidentally locking you out of your own machine

So your choice is really just the default set up being on or off. On is a bit more secure but if you experience any issues then turn it off and don't worry about it.