What does it mean to say that the eukaryotic cell is compartmentalized?

Compartmentalization allows each compartment to perform specific functions without interference from other cell functions. For example, lysosomes can break down cell debris in a compartment without accidentally digesting the cell itself.

It also allow enzymes and substrates to reach higher concentrations than if everything was diluted by the entire cytoplasm. For example, the mitochondria accumulates a large electron gradient in order for the electron transport chain to work.