What is "blue's"

Blue's is the fourth studio album by the Italian singer-songwriter Zucchero Fornaciari. It was released on 15 June 1987, and is credited to "Zucchero Sugar Fornaciari". It has sold an estimated 1.4 million copies in Italy, becoming the best-selling album internationally by an Italian until it was overtaken by his subsequent studio album Oro Incenso & Birra in 1989.