The drama is a literary genre in which fictional stories, actions, and situations that usually belong to human societies are performed by using different elements including actors, costumes, dialogues, scenery, among others and as part of plays, mimes or opera. On the other hand, didactic drama refers to performances that do not only represent different situations or actions but aim at transmitting the audience a main moral or lesson or to instruct or teach the audience something, usually based on morality or desirable behaviors. This occurred during the Middle Ages in which didactic drama was mainly used to instruct the population about the Christian religion. Therefore, it can be concluded the statement that best defines didactic drama is the drama that instructs as this type of drama has the purpose to teach a lesson to the audience.
Y would sound similar to a short E sound when said out loud. You wouldn't pronounce it yee-low, oh-low, or ollow (which is long e, long o, and short o respectively).