Hardly, scarcely and barely are almost used in negative in meaning.
Hardly is chiefly used with any, ever, at all or the verb can:
He has hardly any money. (Very little amount)
He hardly ever goes out.
I hardly ever see him now a day.
The barking dog seldom bites.
Sometimes only hardly can be used with verbs
I hardly know him. (I know him very slightly)
He hardly helped me in my need.
She hardly goes to school.
His father hardly punishes him.
Be careful of being confused in case of using hard and hardly.
He works hard in the field.
He looked hard at me. That means: He stared at me.
He hardly looked at me. That means: (He didn’t give any important glance at me.)
Scarcely means almost not and could replace of hardly as used in the above sentence:
Scarcely any/scarcely ever etc.
But scarcely mainly is used to mean not quite.
There were scarcely twenty students in the class. (Probably fewer in number)
She scarcely comes to our house.
I scarcely watch movie in the cinema hall.
It scarcely rains now a day in our area.
Barely means not more than/just only.
There were twenty people in the field. (Only just twenty)
I can barely check it. (I can only just check it)
I saw barely ten girls here.