(1) Individuals are "not on speaking terms" when a negative emotion (anger, jealousy, pride, etc.) eliminates the willingness to speak with another.
(2) This expression can also be applied to inanimate objects that are not working well together.
Didn't you hear? Michelle and Rachel are not on speaking terms. Rachel is pissed by what Michelle said earlier. I told Rachel she is better off confronting Michelle than bottling up her anger.
My 217 paint brush and I are not on speaking terms, Cecil! Go to the art store and pick up Versamanna brush. I will not look like an amateur in front of the Royal Painters Academy of Florence!