It is so complicated but As a foreigner, Persians will accept your mistakes to making plurals don't worry about it. There are some nouns you can use many ways to make a plural. Don't worry about making mistake. Like پرنده. پرندگان، پرنده ها Like پله پله ها، پلکان Like افسر. افسران، افسر ها Like مترجم. مترجمان، مترجمین، مترجم ها Like حیوان. حیوان ها، حیوانات There is not a complete rule for you to use. But most of the Persian words can make plural with ها and ان but Arabic words have different rules in Persian speaking. Try to learn them like مایع The Plural is مایعات not مایع ها or مایعان or مایعین or مایعجات. Using جات in making plurals means kinds of something. And there are few words that you can use جات for making a plural. like میوه، سبزی، کارخانه، میوجات means Kinds of Fruits, کارخانجات means Kinds of Factories, ...