The Content tab contains all the Items in a project. They're given a structure, that allows you to arrange your Items into a logical way. This could be to reflect the hierarchy of a website, sort blog posts into a chronological order, or an e-book into chapters.
The Content tab gives you an overview of each Item. You can find out the status of the Item, by hovering over the coloured circle to the left of the Item, the number of comments, as indicated by the speech bubble, as well as the template and any assigned people.
You can also see if an Item is overdue, and when the next due date is.
You can also filter by workflow status, so you can navigate to all Items in a particular status, and you can show only your assignments, to focus on the Items you need to work on. From here, you can also reorder Items.