Both are correct, so it would depend on the context. "I have two pieces of candy" is more proper than "I've got".

When you say “two pieces of candy” you are identifying each piece individually. So you use the singular “candy”. When you say I have candies” you are referring to all the candy so it becomes candies in plural form.

THEY COULD BE USED BOTH AS IT REFERS TO SEVERAL SWEETS

both are correct, candy is more common, but depends on context

Both are correct, so it would depend on the context. "I have two pieces of candy" is more proper than "I've got".