What does だったら mean?
だったら is a Japanese noun meaning “if it's the case” in English. It is written as だったら in hiragana, and dattara in romaji. This word is part of JLPT N1 vocabulary.
Example sentence
だったら、私のお願いを聞いて欲しいの。それでチャラ。
If so then I want you to do something for me. That will make us even.