RL researchers often talk about Q-values, Q-tables, and Q-functions, but to me such usage almost always seems like jargon---that is, like apparently precise technical terms that are off-putting to newcomers but really add nothing. In this case the Q- prefix means only that the values, tables, or functions pertain to state-action pairs. There are several pertinent functions that take state-action pairs, for example, that returning the optimal values, that returning the true values for some policy, and those returning the approximation of one of these two values. In most cases, we give these functions different notations, all of which involve the letter Q. That is why I consider the name Q-function to be apparently technical, but in fact imprecise, and thus undesireable, off-putting jargon. If you are just talking in general about the value of an action at a state, then the term I prefer is simply "action value".