also: はっぽん
noun
eight (long cylindrical things)
Counter for eight long, cylindrical objects such as bottles, pencils, trees, or legs. The reading はっぽん is a euphonic variant.
ペンを八本ください。
Please give me eight pens.
ビールを八本買った。
I bought eight bottles of beer.
Compound of 八 (eight) and the counter 本 (ほん, for long cylindrical objects). The reading はっぽん results from gemination of the initial consonant after 八 (はち).