Find the Secure Boot option and change it to Disabled. Save the changes and reboot again. We recommend keeping Secure Boot enabled unless you're sure it needs to be disabled. This article explains how ...

Your system will still work without the security feature, but what are the risks if you disable it?

Acer has fixed a high-severity vulnerability affecting multiple laptop models that could enable local attackers to deactivate UEFI Secure Boot on targeted systems. The Secure Boot security feature ...

I only know that secure boot is a feature that checks the system bootloader is properly signed by something/somebody authorized to do so. So it would make sense that ...