Rosh Hashanah ("the head of the year") is the commemoration of the creation of Adam and Eve. Rosh Hashana serves as a day of reflection on deeds over the past year and to set the tone for the new year.
For Rosh Hashanah, symbolic foods are bread and apples dipped in honey to signify sweet wishes for the new year. A shofar (a hollowed out ram's horn) is blown up to 100 times as sins are symbolically cast off by emptying one's pockets into a body of water.
Justin Timberlake does a mitzvah with a video celebrating the Jewish New Year. Happy 5777!