Rule Number 1: By adding “s”
Rule Number 2:If noun ends with the letters sh, ch, ss or x then “es” is added to make it plural.
Rule Number 3: Some nouns ends in “y” and before “y” there comes a consonant. In this case y is changed to i and es is added. Or it can be said that y is omitted and ies is added.
There is no consonant just before y in ‘toy’ , therefore this rule will not be apply here. And hence correct plural of toy is toys and not toies.
Rule Number 4 : Some noun ends in f. Then we simply replace f by ves. See the table.
Video (Hindi Lecture):