SQL Database Columns

If you have TABLE A with these columns (I put the data type in parenthesis, they are not actually part of the table name):

            LAST_NAME(TEXT), FIRST_NAME(TEXT), MIDDLE_NAME(TEXT), DATE_OF_BIRTH(DATE),

  and TABLE B with these columns:

             LAST_NAME(TEXT), FIRST_NAME(TEXT), MIDDLE_NAME(TEXT), DATE_OF_EMPLOYMENT(DATE)

  and you ran this UNION query:

        Select A.*
        From A
        UNION
        Select B.*
        From B;

    * What column name would the 4th column get?
    * Would the data in the 4th column have much "meaning" or "context" at that point?