• 日本にほん — Japan
• 本当ほんとう — true, real
• 本人ほんにん — the person themselves
• 基本きほん — basic, foundation
• 本屋ほんや — bookstore
• 本日ほんじつ — today (formal)

“本” marks the root of a tree, so it came to mean origin and core. It’s also used for books and appears in everyday words like 日本, 本当, and 基本.