For the positive charge,
When a positive charge is nearby another positively charged body, it will experience the force of repulsion.
Due to this repulsion, the positive charge will move away from the body.
As the potential of the positive charge side is high. Thus, the charge is moving away from the high potential.
Similarly, for the negative charge,
The negative charge under the another negative charge body experience the repulsive force.
As the potential on the negative charge side is low.
Thus, the negative will away from the low potential and move towards the high potential side.