Hello. You did not inform the play to which this question refers, which makes it impossible to formulate an exact answer. However, I will try to help you in the best possible way.
A monologue is a character's speech. This speech the character makes alone because he is expressing his deepest feelings and thoughts. This promotes a broad understanding of the audience with the character's actions, because the character is showing the most intimate of his being. Usually these speeches are emotional and have a strong appeal to the feelings of the audience, the actor and the character.