Answer:
In Act II, Scene 4, she sends the nurse to meet Romeo. Romeo is waiting for her at Friar Lawrence's cell, ready to marry her. In these particular lines, she is losing patience while waiting for the nurse to come back with the news.
In this excerpt, Shakespeare uses the following literary devices:
Simile: "as swift in motion as a ball"
A simile is a figure of speech in which two different things are compared in an entertaining way. This line describes her impatience for the nurse to come back. She says that the nurse is too old, which is why it takes so long for her to come back. If she was younger, she would move as fast as a ball.
Allusion: "And therefore hath the wind-swift Cupid wings."
An allusion is a reference to a person/event/place of particular significance. Shakespeare makes an allusion to a Greek mythology creature, Cupid. Since this creature is often mentioned in a positive connotation and associated with love, it emphasizes her feelings at this moment.
Metaphor: "Therefore do nimble-pinion'd doves draw love,"
A metaphor is a figure of speech which makes a comparison between two completely different things that share certain characteristics. The nurse is here compared to doves, which also serve as messengers that carry love messages.