To understand what means detachment, you need to know about the nature of the Self first, your true nature.  Your true nature is satchitananda. Sat means all the time there, is not coming and going. It's not like when you are born, then you exist. And then you die, and you finish. So, your spiritual nature or your spirit is always there, your consciousness or your true self is always there. So, this is a spiritual approach to life.