The amount of disk space that will be available to you to hold your web site files. The more disk space you have, the more files, databases, and emails your account will be able to store.
Normally, because HTML files are small, a web site (unless it has extensive graphics or database functionality) will be small, as low as 1 or 2 MB in a lot of cases.
Note: MySQL databases and email accounts count against your total disk space.
It has been our experience that many people forget to consider their total usage needs before deciding on a hosting plan. For example, if you will need 10 email accounts, each with 50MB quotas, you will need 500MB or more of disk space.