A long talk; an extended conversation (often informal, sometimes taking up time).
駅で友達と長話をして電車に乗り遅れた。
I had a long chat with a friend at the station and missed the train.
食事のあとで母と長話になってしまった。
After the meal I ended up having a long conversation with my mother.
彼はいつも長話をするので、話を切り上げるのが大変だ。
He always talks at length, so it's hard to bring the conversation to an end.