Final answer:
You need to boot into single-user mode or recovery mode to fix the issue of an incorrect entry in /etc/fstab that can't be mounted.
Step-by-step explanation:
In order to fix the issue of an incorrect entry in /etc/fstab that can't be mounted, you need to boot into the single-user mode or recovery mode.
These modes provide you with a root shell that allows you to make changes to your system configuration files, such as /etc/fstab. From there, you can edit the file and correct any incorrect entries to ensure the system can boot properly.
By booting into single-user mode or recovery mode, you can fix the issue and get your system up and running again.