Hello, and welcome to Hubpages.
When you initially create a hub you can select a category for the title to be listed in. Once you have more than one Hub you will see all the different categories you have them titled under. When you are viewing your hubs using the "my account" link you will see a total of all the hubs published if you're filter is set to "select a category". If you click on the arrow to see your selection of categories, and choose a specific category, then the list of hubs showing will change to only hubs in that category.