What does the Korean expression han bon do mean?

"한번도" (han bon do) is a Korean expression that means "never" or "not even once".

Here's how it breaks down:

* 한번 (han bon) means "once"

* 도 (do) is a suffix that emphasizes negation, meaning "not even" or "not at all".

Examples:

* 저는 그 영화를 한번도 본 적이 없어요. (jeo-neun geu yeonghwareul han bon do bon jeogi eopseoyo.) - "I have never seen that movie."

* 그는 한번도 화를 낸 적이 없어요. (geuneun han bon do hwareul naen jeogi eopseoyo.) - "He has never gotten angry."

Note: The word order can be rearranged slightly depending on the context. For example, you could also say "본 적이 한번도 없어요" (bon jeogi han bon do eopseoyo), which means the same thing.