All about the kanji, part 10: 本

One reason that 本 ranks so high on the frequency list of kanji is because it appears so often next to 日 to make 日本, Japan. But even on its own, it has many readings, both in its on reading of ほん (where it means 'book', but also 'main, head, real' and serves as a counter for long cylindrical things, such as bottles, glasses, and scrolls of paper) and in its kun reading, もと (origin, source, base, foundation, cause, and a number of more obscure meanings).
This is why a simple compound like 一本 (いっぽん) can mean 'one cylindrical thing', or 'a certain book', or even, for some unfathomable reason, 'an experienced geisha'.
Repeating the kanji twice, written as 本本 or 本々 (々 means 'repeat previous kanji') is pronounced もともと and means 'originally'. 本国 (ほんごく) means 'one's own country'; 本人 (ほんにん) is 'the person himself'; and perhaps surprisingly, it's also the first half of 本当 (ほんとう), meaning 'truth, reality' (and so 本当に means 'in truth' or 'really').
Some more combos with kanji we know already:

• 本日 (ほんじつ) is another word for 'today'
• 本年 (ほんねん) is 'this year'.
• A three-kanji compound is 日本一 (にほんいち), meaning 'Japan's best, number one in Japan'.
• And finally we have all 3 parts to make 日本人 (にほんじん), a Japanese person.

There are tons more compounds, so it's best to leave those until we find the kanji 本 combines with.