According to Osho, being open means being without mind: the mind is a transparent glass wall that imprisons through labels, beliefs, and prior conclusions. Openness arises by dropping mind through meditation and sannyas, living from not-knowing, innocence, and direct perception. This is the truly scientific, religious attitude: meeting facts and life without prejudice so truth can reveal itself.
Being open is like taking off invisible glasses of opinions so you can look at life fresh, without labels.