Recall the concepts about kinetic and potential energies.
Kinetic energy = The energy due to the motion of the object
Potential energy = The energy due to the position of the object.
Position 1:
At this position, the kinetic energy is minimum due to the non-motion of the roller coaster but the potential energy is maximum due to the height.
Position 3:
At this position, the potential energy is minimum since the height is almost zero but the kinetic energy is maximum due to the motion.
Position 2:
The kinetic and potential energy of the roller coaster car will be equal to each other at a point that is halfway between positions 1 and 3 that is position 2.
At this point, the roller coaster has enough motion and height such that kinetic and potential energy will be equal to each other.
The kinetic energy is increasing and the potential energy is decreasing but at position 2, they will be equal.