For plurial French, the standard rule is :
1/You should added “S" with a name in the singular to make plural.
Ex : Un chat; des chats; Une histoire, des histoires, etc.
2/Names which ending in “ou” follow the standard rule.
Except : bijou, caillou, chou, genou, hibou, pou et joujou with a "X" in plural;
Ex : Un minou, des minous. Un bijou, des bijoux.
if I have forgotten something, complete please !
Ex : Un cheval, des chevaux; but un chacal, des chacals.