Rule 1 - If in the end of a Noun there is ‘s’, ‘sh’, ‘ss’, ‘z’ or ‘ch’ then to make it plural we add ‘es’ in the end of the noun. For example: Ass-Asses , Box-Boxes.
Rule 2 - If a singular noun contains ‘f’ or ‘fe’ in the last of the word, we add ‘ves’. For example:Knife - knives , Leaf - Leaves.
Rule 3 - If a noun ends with ‘Y’ and before ‘Y’ that contain a consonant then to make that plural we can remove ‘Y’ with the ‘ies’. For example:Army - Armies , Lady - Ladies.