The best description of the structure of the play would depend on the specific play in question, but if we are looking for a general description that fits many plays, "naturalistic dialogue between characters in a realistic setting" is often a strong choice. This description encapsulates the essence of many modern plays that focus on character interactions and realistic portrayals of life. However, if the play is more comedic or has elements of farce, "rapid farce with rhythmic action, entrances, and exits" could also be appropriate.
If you have a specific play in mind, I could provide a more tailored response!