The Tables stage is used to select which Salesforce tables will be included in the search. All searchable fields in selected tables in this stage will be searched.
By default, commonly searched tables are visible. To view additional tables select the corresponding checkbox in the Table Groups selector on the left.
The default behavior of the table selector is to show table labels instead of the table API Name. To view API Names instead of labels, check the Show API Names checkbox to the right of the Filter input: