Double-click a field in the table to select it as part of the result. It will appear in the lower Selection window.

tj-selected-columns

Alias
It defines an alias for the column, to rename the column in the result.

Aggregate Function
It define an aggregate function. Following options are available:
AVG: Average,
COUNT: Count,
MAX: Maximum,
MIN: Minimum, and
SUM: Sum.

If you select an aggregate function, an Alias must be defined.

Check the following example, that counts the number of description languages of each material.

tj-aggregate-count

On the right side you have the options to move up, move down or delete the fields.