A girl who was playing beautiful music

A very nice and secret music 🎶 I heard from some place, it’s so peaceful and very simple tones though but it’s very impressive, when my wife and I were strolling through the park. I was attracted by it and followed the way that music played from. It’s about 7pm, it’s not that dark so I found the site easily. Two girls, mother and her daughter, were playing a instrument that I never seen before on a picnic blanket. I chatted with them and asked some questions about the instrument. Then I took this pic after got them permission. Sorry about the flashlight of iPhone that makes the picture looked a bit strange.