this poor friend is covered in what is known as 'honeydew'. these little droplets have seeped out of holes left behind on the underside of the leaf by sap sucking bugs like aphids, mealybugs, scale or whiteflies
the underside of our leaves can tell us so much more about what's going on with a plant. bugs tend to hang out there because they are protected from the elements.
this one needs a good shower, wipe down and a coating of insectisidal soap. don't forget to check on them often and repeat the treatment plan as much as every day until signs of pests have disappeared