Answer:
Yes, a force can be negative. Force is a vector quantity, adopting direction from the acceleration.
Acceleration comes from the equation "F = ma", and we know mass is an inherent object. Therefore, direction comes from the direction of acceleration.
If acceleration is moving in a negative direction, then force becomes negative. Let's say forward is a positive direction and backwards is negative. A car from stop to moving in reverse is exerting a negative force, assuming their velocity continues to increase. Once they maintain a constant velocity, the net force is 0. If they moved forward, force is positive.