Step 1: Identify the Drive

lsblk

Step 2: Unmount (if needed)

sudo umount /dev/sdX1

Step 3: Format to ext4

sudo mkfs.ext4 /dev/sdX

Step 4: Create Mount Point

sudo mkdir -p /mnt/BackupExternal

Step 5: Mount Drive

sudo mount /dev/sdX /mnt/BackupExternal

Step 6: Make Persistent (fstab)

Check this guide here: https://desktopnerds.com/blog/mounting-drives-in-linux-fstab-explained

Warning

Formatting erases all data on the drive.

Conclusion

ext4 is the most stable and widely supported filesystem for Linux systems.