The countable and uncountable situations are as follows:

1. When chocolate is explained as a brown sweet food that can be made into candies or add flavor to other foods, it is Uncountable noun. For example, when referring to "Chocolate is a commonly used condiment," it is an uncountable noun.

2. When chocolate is explained as a candy made of chocolate, it is a countable noun. For example, when referring to "a piece of chocolate candy sold in a store", the English expression is "a bar (slab, block) of chocolate", which is a countable noun. Countable nouns can have S at the end.