When you add a table, its name (Table 1, for example) is shown by default. You can edit the name or hide it. No tables in a spreadsheet can have the same name.
Click the table, Control-click the row number for row 1, then choose Hide Table Name or Show Table Name.
Triple-click the name at the top of the table, then type a new name.
To enclose the table name in a border, click the table, then click the Table tab at the top of the sidebar on the right. Click the Table Outline pop-up menu, choose an outline style, then select the “Outline table name” checkbox.
If you don’t see a sidebar, or the sidebar doesn’t have a Table tab, click 
in the toolbar.