How can a system have reactions if it's a equilibrium

We can tell a reaction is at equilibrium if the reaction quotient (Q) is equal to the equilibrium constant (K). ... To re-establish equilibrium, the system will either shift toward the products (if K > Q) or the reactants (if K < Q) until Q returns to the same value as K

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.