Opening up means expressing yourself, showing , telling and freeing yourself in front of others, how to feel about the person or how do you feel comfortable with the person or not, telling them regarding it, do not shy or hesitate in starting a conversation with someone, stand for yourself, show and express, open up be comfortable in front of others. It means to confess something to him/her about them or yourself. It means Revealing your secrets or hidden things to someone which you will not be sharing with somebody else, talking about your skills, dreams, family and problems to someone.