The thing that I wanna know is how you use plural, singular and just noun.
I always get confused when I make sentences in English. For example, I'm at a chocolate shop and I want to let my baby know the thing she is looking at is chocolate. I don't know 'It is chocolates' is right or 'It is chocolate' is right or 'It is a chocolate'
I understand your question, but you have chosen a poor example. "Chocolate" can be either countable or uncountable, depending on context: That is chocolate Those are chocolates
can both be correct, depending on what you are saying.
Certain foods (for example, rice, or wine) are normally treated as uncountable, and thus use a singular verb: Question: What do I see on that dish?
Answer: It is rice.
Other foods are normally treated as countable, and use a plural verb: Question: What do I see that dish?
Answer: They are pork chops (or chicken wings, or eclairs, or muffins, or cupcakes, etc.)