then; and then; in that case; if so
Casual spoken conjunction used to connect events or to present a consequence or response to what was just said. Similar to そうしたら but more colloquial.
駅に着いた。そしたら、友達がもう待ってた。
I arrived at the station. Then, my friend was already waiting.
"It might rain tomorrow." "In that case, the picnic is off."