What do you understand by the clockwise and anticlockwise moment of force? When is taken positive?

Hint: Moment of force is the tendency of a body to rotate about a specific point or axis. Direction of the moment of force is the same as the tendency of the body to turn in some direction.

Complete answer:
Moment of a force is a measure of its tendency to cause a body to rotate about a specific point or axis. This moment of force is different from the tendency of a body to move, or translate, in the direction of the force as this moment of force is a static force. This occurs when a force is applied so that it does not pass through the centroid of the body.

The direction for the moment of force is defined as follows:
If the effect on the body is such that the body is to turn in anticlockwise direction then the moment of force is said to be in anticlockwise direction. And if the effect on the body is such that the body is to turn in clockwise direction then the moment of force is said to be in clockwise direction.

The moment of force in the clockwise direction is taken as negative. And the magnitude of the moment of force in the anticlockwise direction is taken as positive.

Note:Remember that although torque and moment of force have the same units but they are significantly different. Moment of force is a static force. Whereas torque is a dynamic force as it brings about the motion. The moment arm is always the perpendicular distance between the centre of moments and the line of action of the force.