This can be very helpful to know, for various reasons. You will need to be logged into your dedicated server or VPS server via SSH, as this command will require you to be logged in via SSH.
du -ha /home/user | sort -n -r
Replacing "/home/user" with the directory for which you want to know the disk space used for that particular directory. You will see an example output like below
root@localhost[~]# du -ha /home/user | sort -n -r