A Table is a stereotyped Class. It is drawn with a small table icon in the upper right corner. You typically use this element in Data Modeling diagrams.
A Table element has a special Properties dialog, with settings for database type and the ability to set column information and data-related operations such as triggers and indexes. When setting up a Table, make sure you set the default database type for that Table, otherwise you do not have any data types to choose from when creating columns.