In your Data Sources, table columns can be browsed and displayed by Table but also by Categories (click on the node Columns by categories)

The categories are used to build the Tree View displayed to select elements when you build your models, so it is interesting to have good names and hierarchies in your categories.

By default, the column category is the table name, but you could (should) change this to give a name that can be easily understood by people building the models.

You can define sub-categories using the '/' characters: e.g. 'Orders/Order Dates' will create a sub-folder 'Order Date' under the 'Orders' node.

You can rename globally your categories by expanding the node Columns by categories then click on the category you want to modify, and finally modify the Path property in the editor, all columns will be modified...