expression
speaking of ...; when it comes to ...; as for ...
Used to pick up a topic just mentioned and add a related comment. The literal meaning 'if one were to say ...' is rarely used in modern conversation; the phrase functions as a fixed topic marker.
夏といえば、やっぱり海だよね。
Speaking of summer, it's definitely the beach, right?
彼といえば、最近全然見かけないね。
As for him, I haven't seen him at all lately.