Complex sentence: Leaves, their main food source, provide very little energy or nutrients, and do not digest easily, so sloths have large, slow-acting stomachs with multiple compartments in which symbiotic bacteria break down the tough leaves.
Split into simpler sentences: Leaves, their main food source, provide very little energy or nutrients, and do not digest easily. Sloths, therefore, have large, specialized, slow-acting stomachs with multiple compartments in which symbiotic bacteria break down the tough leaves.