What does it mean that a glove is not suitable for acid foods?

It can not be used in contact with foodstuffs with a pH lower than 4.5 (vinegar, cider, juice or simple or concentrated vegetable juices, fruit nectars, lemonade, syrup, bitter, vegetable infusions, coffee, tea , Non-alcoholic drinks, energy and the like, flavored water, liquid coffee extract, preserves, yogurt, feta, mozzarella, mayonnaise, mustard).