They are equal in magnitude.
If no force is applied to an object, the object will not accelerate - its velocity won't change.
If there are unbalanced forces acting on an object with the bigger force in the opposite direction to its movement, the object will slow down or decelerate. The net force will oppose the object's motion, causing it to eventually come to a stop or change its direction.
A force that acts on an object, but does not cause any movement (specifically, a change in velocity) of the object, is (by Newton's law) equally and opposite balanced by other forces.
Three things that can cause a change in acceleration are a change in the net force acting on an object, a change in the object's mass, or a change in the direction of the force acting on the object.
inertia
The motion of an object is determined according to Newton's laws of motion. In particular, acceleration is proportional to force. If you change the force, you change the acceleration. There are many details beyond that, but that is the simple answer to a very broad question. NOTE: Neither the force nor a change in it has any effect on the motion of an object unless the force happens to be acting on the object.
You can change the weight of an object by altering its mass or the force acting on it. Increasing the mass of the object will increase its weight, while decreasing the force acting on it will decrease its weight.
Opposing force
An object that has an unbalanced force acting on it will accelerate in the direction of that force.
False. Balanced forces acting on an object will not change the object's velocity. When forces are balanced, there is no change in the object's velocity as there is no net force acting on the object.
If there is no net force acting on an object then the movement of the object doesn't change. If it is sitting still, then it remains sitting still. If it is moving, then it continues moving at the same speed in the same direction.
A net force is the sum (vector sum) of all forces acting on an object. If there is a net force acting on an object, the object will accelerate - its velocity will change over time.