Every is a determiner. It is used before a singular noun.
Every child needs love. (NOT Every children need love.)
Every day is different.
Every mother loves her child.
Before a pronoun or a noun with a determiner we use every one of. Note that every one of is followed by a plural noun or pronoun. The verb is usually singular but can be plural in an informal style.
Every one of my friends loves soccer. (NOT Every my friend loves soccer.)
Every one of the children was happy.
In negative structures, we use not every.
Not every kind of bird can sing. (More natural than ‘Every kind of bird cannot sing.’)
The pronoun used to refer back to every is usually singular, but can be plural in a less formal style.
Every boy has handed in his work. (Formal)
Every boy has handed in their work. (Informal)
Every student was asked to bring his or her hall ticket. (Formal)
Every student was asked to bring their hall ticket. (Informal)
Every can be used before a plural noun in some expressions referring to intervals.
Buses leave every ten minutes. (NOT Buses leave every ten minute.)
I see her every few days.
Common expressions with every
Every is used in some common expressions.
She visits her parents every single day.
We meet every other day. (= every second day)