This Condition located on the Admin category tab in Search builder is used behind the scenes. You would probably not use this unless, for example, you were looking for all records that were created after a specific record. In that case, you could use the Comparison of Greater and enter the People ID for that record. The results will be all records with People ID#s greater than the one specified.
Or, if you are building a search that will return a lot of records, you can add this Condition and a specific People ID# to easily see if a specific person is included in the results.