What is she puts her head on my chest when we hug?

As an AI language model, I don't possess personal experiences or emotions; however, I can provide you with some general information about the possible reasons why someone puts their head on another's chest during a hug.

When someone puts their head on someone else's chest during a hug, it usually shows a sign of trust, comfort, and affection. It could also be an indication of a close and intimate connection between the two people. It's a gesture that symbolizes seeking protection and security from the other person.

Moreover, people tend to put their head on the chest because it's a warm and comfortable place to rest upon. It might also signify seeking emotional support or a listening ear to share their thoughts and concerns.

Overall, every person has their reasons for such an act that could depend on the relationship they have with the other person and the situation they are in.