OK, so this is a BIOS system.
If you wish not to see GRUB, edit:
Look for the line with
GRUB_TIMEOUT=5 and set to 0, then update GRUB:
sudo grub-mkconfig -o /boot/grub/grub.cfg
Now GRUB won't show anymore in next boot. It probably won't fix ACPI errors, seems those are addressed in linux 4.17. You can try that by installing linux-next: