The distinct key word returns a distinct result for all of the columns in the select statement.
Where you only need the UserSex column to be returned, it should be the only column in your select statement
SELECT DISTINCT UserSex
FROM users
IF you *did* need all of the other columns returned, dont use distinct, use GROUP BY:
SELECT UserAge,UserSex,UserTypes,UserArea,UserEthnicity
FROM users GROUP BY UserSex
For more information on the DISTINCT key word:
sql_distinct.asp
For more info on GROUP BY:
sql_groupby.asp