Tension is described as a force that acts in opposition to another force, such as gravity, particularly in scenarios involving ropes or cables. When a weight is suspended from a rope, the tension in the rope counteracts the downward force of the weight, maintaining equilibrium. Visual representations can aid in understanding this concept, though specific resources were not provided in the discussion. The explanation clarifies that for a system to be in equilibrium, the tension must equal the weight acting downward. Understanding tension is crucial for grasping basic physics principles related to forces and equilibrium.