Mala (Tibetan prayer beads) are strings of beads used as an aid to prayer and the recitation of mantras in the Buddhist religion, much as a Catholic rosary is used (both share name similarity as well- both ‘rosary’ and ‘mala’ refer to garlands of flowers). A mala is held in the hand and rotated, one bead at a time, while mantras are recited. Beads of varying number and material are used for various purposes: crystal for clearing obstacles, bone for subduing demons, etc.
A kapala-mala is a mala string made of skulls carved from human bone. Pure Land and other Buddhist traditions use a double-fringed strand of beads called juzu (counting beads) or nenju (“thought beads”). These typically consist of 108 small beads symbolizing the 108 earthly desires which must be overcome; some have larger focal beads to represent the Bodhisattvas.
Juzu are used for prayers in much the same way as a Catholic rosary, or may simply be held during meditation or contemplation. *A Bodhisattva (Sanskrit, “essence of enlightenment”) is a highly spiritually developed being who stops short of Buddhahood in order to aid others in attaining enlightenment.