i am just curious how do "quantities" in auction work?

for eg.

a seller puts 5 pencils for sale
Buyer A bids 5 pencils for $1 each
Buyer B bids 1 pencil for $2

now who gets what? B will get 1 pencil then A gets? 4 pencils? will he agree to that?

Yes he will agree as it is an outbid.
If he wants them all again he needs to bid over $2 but some systems will need a bid on all 5 articles at the same price, so over $2 and that 5 times.

ooo ok thanks for the info