着have a lot of meaning, 笑着说 here you can think as a grammar like” verb1+着+verb2 ” it is a state like: 坐着吃饭 eat with a state of sitting 站着上课 have class with a state of standing 躺着睡觉 看着电视吃饭 哭着说话 笑着打电话 ...... hope that could help you:)