Thank you!

The content hash is the unique hash for the file (so if the file changes, the hash changes) and the 8 is how many characters of the hash to use.

You can truncate hashes to get shorter file names, but this increases the chance of collisions (a scenario where you change the file, but the part of the hash you’re using just happens to stay the same).

Using just 6 or 8 characters is common and still extremely unlikely that a file change would not result in a hash change.