`mkfs.ext4` - create an ext4 filesystem

mkfs.ext4 [options] DEVICE

Options you will use

-L LABEL: Set the volume label (mount it with LABEL=... in fstab).
-m PERCENT: Reserved blocks for root (default 5%).
-i BYTES_PER_INODE: One inode per this many bytes: smaller means more inodes (for millions of tiny files).
-N NUMBER_OF_INODES: Create exactly this many inodes. Fixed for the life of the file system.

Try mkfs.ext4 in a real terminal Free, in your browser - a real Ubuntu terminal to try it in, with missions that check your work.