Meaning of the word "best selling author" in English

What does "best selling author" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

best selling author

US /bɛst ˈsɛlɪŋ ˈɔθər/
UK /bɛst ˈsɛlɪŋ ˈɔːθə/

Noun

an author whose books have sold in very large numbers

Example:
J.K. Rowling is a renowned best-selling author.
His latest novel made him a best-selling author overnight.