Question

When a pendulum is at the position all the way to the left when it is swinging (at the top of the arc), what is true of the kinetic and potential energy?

Answer 1

kinetic 0, potential maximum.

Answer 2

Kinetic energy is greatest when it passes through the center, lowest point. Potential energy is zero there.
Potential energy is greatest at the left and right ends, where it stops and heads back the other way. Kinetic energy is zero there.
So the pendulum is constantly converting its energy from one state to the other.
Pull it to the side and hold. Energy is all potential. Then let it go.
One complete swing ... to the other side and back to your hand ... does this:
Potential & let it go -> kinetic -> potential -> kinetic -> Potential & catch it.
. . . . . . . . . . . . . . . . . . center . . . . . . . . . . . . center