What is a 'CDI unit' on a Motorbike?

the cdi unit on a bike is what they use since thyve done away with points the unit is what gives you youre spark at the sparkplug if its not workin the bike wont run and i dont think you would get 1 for that price because its not a thing you would have to go to the maker of the bike i wouldnt touch it for that to go something had to cause it until you fix that the 1 you put in wont last long theres plenty of bikes out there or tell the owner to fix it wait and see how long it lasts