As Buddhism moved from country to country, and culture to culture, bits of Hindu and Tantric elements were mixed into the teachings. The Juzu is one such item. Traditionally, it is an aid in chanting, serving as a counter (so you can keep your place), although a whole mess of mystical 'meanings' and powers came to be associated with the Mala beads themselves and the usual number of beads: 108 (or a divisor thereof).
Number of beads:
The formal nenju has 108 koshu 'children'/main beads, plus either one or two larger boshu 'parent' beads.
[The 108 koshu represent the 108 bonnou (earthly desires, worldly & or evil passions) which the follower of the Dharma seeks to overcome.]
There are also 'informal' nenju. These are commonly 1/4-size, having 27 koshu and one boshu parent-bead. However there are also informal nenju with 18 koshu (1/6th-size), 36 koshu (1/3rd) 54 koshu (1/2)
For just some of the many meanings of '108'. have a gander at this. It is wonderful: