Why hosting space is almost full

Hello, I am a newbie in the hosting administration, so please suggest me some easier process to resole my issue. I am using aws ec2 instance to run my websites and using WHM and cpanel to manage it. I have 79 GIB space for my ec2 instance which is almost full (94%). Now, when I go to my cpanel and see space used it is showing just 22.31 GB used. Where rest of the space is going ? Can someone please help me figure out and fix ?? I am attaching some screenshot as well..