Pineapples, same as many other fruits, are a vital source of vitamins and minerals. The obvious health benefits, perhaps in order of importance are:
1. source of dietary fiber
2. source of vitamin C, with some varieties being low while others are quite high
3. source of rapidly assimilated carbohydrates (sugar)
4. source of mineral elements (potassium, calcium, magnesium, phosphorus)

     Some claims pineapple aids in digestion because of the presence of the enzyme bromelain, a protease, but there doesn't seem to be any scientific evidence to support this claim.