three (long cylindrical things)
Used as a counter for three long, thin objects such as bottles, pens, trees, or fingers.
冷蔵庫にビールが三本ある。
There are three bottles of beer in the fridge.
I bought three bottles of beer at the supermarket.
鉛筆を三本ください。
Please give me three pencils.
In hanafuda, a hand containing three cards of the same suit. Domain-specific term.
See also: 手役
手札に三本ができた。
I got three-of-a-kind in my hand.
彼はクラスで三本の指に入る成績だ。
He has one of the top three grades in the class.
三本 (さんぼん) is 'three long cylindrical things' (bottles, pens, etc.), while 三分 (さんぶん) means 'three parts/portions' — the readings sound alike but the counters differ.
three legs; two legs and a cane
three-of-a-kind of April, May, July, or December suit
three-bout contest; three-game match; best-of-three
triple feature; three-part program
threefold ipponjime clapping
Standard kanji spelling for counting three long cylindrical objects.
Numerical variant; common in informal writing, lists, or when space is limited.
Compound of 三 (san, 'three') and the counter 本 (hon, 'long cylindrical object'), with rendaku voicing to ぼん.