Nothing to worry about especially if it boots fine and loads your graphical environment. It's just a grub warning message because grub doesnt play well with (presumably) nvidia. You could probably make some tweaks to remove the error but there's really no reason to bother.

Let me guess, you have an Nvidia card?

Red Dead Pixel Redemption.

I had this error several times (also cases where it would not boot afterwards). It usually appears after installing Nvidia drivers.

The first two lines seem like they probably came from X, the old standard UI system for *nix. The last line is just saying that your 2nd partition on your 3rd disk was checked with no errors found. This is fine.

Given that the UI then starts up you can ignore these messages. They're there in case the system fails to start up after that point.

Did you install Ubuntu alongside Windows, or do a fresh install after wiping?

According to DDG it's a Grub issue. There are a couple of things you could try by searching that error message.

What are your PC specs? Make sure CSM and Secure Boot are disabled in the BIOS.