This refers to how much storage space you are allowed on the server and can be used for all web related files including, HTML files, databases, images, CGI-scripts, multimedia files, email messages, and so on.

To get an idea of just how much disk space you get;
50 MB is equivalent to about 1000 average web pages!

Each hosting plan includes generous disk storage ranging from 200MB to 600MB per month. Additional space can be added as needed.