In actual sense a monologue is a speech, delivered by one person, or a long one-sided conversation, without any input or interference by others. In Hindi it is also called ‘Ekapatrika’ or also called the mono-act in simple sense.
The Greek root word monologos translates to “speaking alone,” and that’s a monologue: one person doing all the talking. In theatre, sometimes a character has a monologue that they perform. In a simple way and a perfect example is, we all might have an internal monologue-where you talk to yourself to better understand some dilemma. Some people talk forever in a constant monologue, never letting you speak.
If two people talk back and forth, it’s a dialogue, which is different and probably more fun for everyone.