Which kind of polarity do water-soluble and fat-soluble substances respectively have?
Water-soluble substances are polar molecules, i.e., they have electrically charged areas. These molecules get the explanation "water-soluble" because they are soluble in water, a polar molecule too.
Fat-soluble substances are non-polar molecules, i.e., they are electrically neutral. They get the explanation "fat-soluble" because they dissolve other non-polar substances.