This is the 2725th most frequent Japanese word.
笑っ
"笑っ" means "laughed" or "smiled."
In this sentence, '笑って' (waratte) indicates the action of laughing as a response to something amusing.
その冗談でみんなが笑っていました。
Everyone was laughing at the joke.
Here, '笑っ' demonstrates a somewhat unexpected reaction to an error, possibly to lighten the mood.
彼は失敗して笑ってしまった。
He laughed after making a mistake.
The word '笑って' is used as an imperative form here, requesting people to smile during the photo-taking process.