see in phrasal verb ( see also ↑ see )
1 . not know what somebody sees in somebody ( also what does somebody see in somebody? ) used to say that you do not know why someone likes someone else:
I don’t know what she sees in him.
2 . see something in somebody/something to notice a particular quality in someone or something that makes you like them:
He saw a gentleness in Susan.
3 . see somebody in to go with someone to make sure they arrive at a building or room:
He took her home and, after seeing her in, drove off without a word.
4 . see in the New Year to celebrate the beginning of a new year