what happens when one more unit or one less unit is produced than the equilibrium evel of output?

The equilibrium output is that level of output wherein the market demand equals the market supply. Now, if one more unit of output is produced than the equilibrium level, then this will lead to a situation of excess supply. That is, if one more unit is produced than the equilibrium level then the demand will fall short of the supply, resulting in excess supply situation. On the other hand, in case one unit less than the equilibrium level is produced then this will lead to a situation of excess demand. That is, if one unit less is produced than the equilibrium level then the supply will fall short of the demand, resulting in excess demand. The two cases of excess demand and excess supply are also covered in our study material in an extensive manner. You can find them in Microeconomics- Market Equilibrium (Lesson 1) of our study material.