Selecting this option from the Database Navigator will open a window that allows you to perform a "CHECK TABLE" command on all MyISAM and InnoDB tables (the command isn't supported for other table types).
There are several options to set before checking, this can be done via the drop down menu on the Check Tables button in the window.
Check and Repair Tables
Check the MySQL documentation for the options on CHECK TABLE.
The second button allows you to perform a "REPAIR TABLE" command on the selected tables - again, several options are allowed and these can be set via the drop down menu on the Repair Table button.
Note:
REPAIR is only performed for MyISAM tables.