The keyword insertion code in an ad’s headline is “Buy {KeyWord:Books}.” The ad appears when someone searches on “flower books” and the query matches a broad match keyword, “gardening books.” How would the headline read?
Buy flower-arranging books
Buy plant books
Buy gardening books
Buy keyword
Explanation:
Read the line and the query expanded to a broad-matched keyword in the account, “gardening books.” It means, “Gardening Books” is already added and is being triggered when “flower books” is searched. That’s why, added keyword i.e. “Gardening Books” will be fetched and added in the ad copy.
Read more here: https://support.google.com/adwords/answer/2454041