Effectively, it is nothing else but a set of bells in a tower are synchronized with a keyboard and played from it. Try to visualize it.
Read the full Wikipedia article here:
Carillon carries the following dictionary definitions:
1. A stationary set of chromatically tuned bells in a tower, usually played from a keyboard.
2. A composition written or arranged for these bells.
Master tips for Carillon:
When one is in the midst of singing ‘Christmas carol songs’, one can find the carillon bells being played out loud.