An interjection used when starting a topic, preparing to do something, or pausing to think; similar to 'well' or 'now' in English.
さあて、今日の仕事を始めよう。
Well then, let's start today's work.
さあて…次はどこに行こうか？
Now then... where shall we go next?
さあて、問題をどう解決するか考えないといけない。
Well, we have to think about how to solve the problem.
さあて、彼は来るかな？
I wonder—will he come?