Yes, the phrase ‘time flies’ is indeed a metaphor. It is used to describe the swift passage of time in a way that is easy to understand. Just as a bird or an airplane can travel quickly through the sky, this expression indicates that time seems to move rapidly when we are busy, engaged, or having fun.
This metaphor emphasizes our perception of time rather than its actual passage. Sometimes, when we are deeply involved in an activity or enjoying ourselves, we may feel like time is slipping away faster than it actually is. Conversely, during dull or uninteresting moments, time may seem to drag on. Therefore, ‘time flies’ captures this common experience in a vivid way, making it relatable for many.