What are Mala Prayer Beads?

A mala is a symbol of devotion, but why 108 beads?

One theory is that a person takes 21,600 breaths in a day. If we subtract hours of the night, then we are left with 10,800 breaths. According to this, the religious teachers said a person should recite God’s name 10,800 times in a day but God’s name recited once with faith is equivalent to 100 times. So based on this argument it was decided to have 108 beads in a rosary/mala.