Tashlich means casting off. It’s also a name of a prayer.
The days between Rosh Hashanah and Yom Kippur are called The Days Of Awe. Jews reflect on their behavior the previous year and ask forgiveness from God and from their friends and families for sins they committed against them. On the first day of the New Year, it is customary to go to a body of flowing water to say the prayer of Tashlich and to toss away bread crumbs into the water. This act symbolizes tossing away last year’s sins and letting the water carry them away.