That’s the way to play the helm-shaped psaltery.
The psaltery is a great casual alternative to a guitar since it doesn’t require formal instruction. Playing is really easy to learn. It’s perfect for small hands and is a genuine alternative to the plastic toys with all of the buttons and flashing lights. At least it has 6 strings and made of wood. If you want an instrument that your child can grow with, I’d recommend to buy a ‘real’ one. It will also look nice on a shelf if it survives the early years!