Key Idea: The Quantum particle is living in all possible states simultaneously until it is observed by an observer. During the observing period, the quantum particle lies in a single state.
To understand this, let us consider a person who has placed the ball (particle) inside the Green box. So, Until the position of the ball remains unobserved by an observer. According to quantum superposition in this unobserved period, the ball inside the green box lies in all the possible positions (or in states if different states are possible) inside that box.
