Block styles for tables (<table>) come from Bootstrap (table styles).

1. Select a table by clicking anywhere within the table
2. Click the "table" word beneath the RTE
3. From the Block style dropdown menu, choose "table" to apply the default table style
4. If an additional style is desired, continue to choose another style from the Block style dropdown menu. Additional styles may be mutually-exclusive (so choosing a different option may automatically replace any that has already been selected).

These are the available table styles (all table cell values are the same except for the selected Block styles).