What is fish out of water?

The expression "fish out of water" is a metaphor that refers to someone who is in an unfamiliar or uncomfortable situation. It is used to describe a person who is not in their normal environment or who is struggling to adapt to a new environment. For example, a person who is from a small town and moves to a big city may feel like a fish out of water. They may be overwhelmed by the size and complexity of the city and may struggle to fit in.