Final answer:
The bell in Macbeth signifies the time for King Duncan's murder, serving as a go-ahead signal for Macbeth, and foreshadows Duncan's fate. The scene closes with a rhyming couplet.
Step-by-step explanation:
In Shakespeare's Macbeth, the ringing of the bell signals to Macbeth that it is time to proceed with the murder of King Duncan, serving as a signal from Lady Macbeth that she has made the guards and it is safe to commit the murder. Macbeth refers to the bell as a 'knell' that summons Duncan to heaven or hell, effectively marking the end of Duncan's life and the finality of Macbeth's treacherous act.
The scene ends with a poetic form known as a rhyming couplet, which is a pair of lines that rhyme and have the same meter. This rhyming couplet signifies the end of a scene or act in many of Shakespeare's plays, providing a strong closure with a rhythmic sound.