like a fish out of water

Like a fish out of water means to feel awkward as you are in a situation which is not familiar to you and you look or fee very different from the people around you. A fish out of water feels out of place because they belong in the water, therefore when used figuratively, this idiom is making a point that you feel extremely awkward in the given situation. This is often used when someone is at a new place with new people they dont feel comfortable with yet.