Why equilibrium is dynamic in nature?

The word ‘dynamic’ itself is the clue. It means the reaction has not simply stopped. Instead, a lively balance is achieved.

At equilibrium, the forward reaction and the reverse reaction are both happening. Crucially, they happen at the exact same speed. Think of an escalator in a busy mall. People are constantly moving up, while others are moving down. If both rates are equal, the total number of people on the escalator seems constant at any given moment.

Similarly, reactant molecules are continuously forming products. At the same time, product molecules are breaking back down into reactants. The overall concentrations do not change, but the system is full of constant, unseen activity. It is active, not static.