Singular - one. Plural - more than one.
If the noun ends with s, ss, x,
ch, or sh (the spitty sounds),
add -es to make it plural.
ex: one bus, five buses
one bench, four benches
one box, two boxes
one wish, three wishes
If the noun ends with a consonant and y,
change the y to i and add -es to make it plural.
ex: one party, seven parties
one belly, ten bellies
If the noun ends with a vowel and y, then
just add -s to make it plural.
ex: one day, six days
one key, two keys
If the noun ends with f or fe, change the f to v and add -es.
ex: one wife, two wives
one shelf, three shelves