How are these pouches opened
1). The decorative bow could be on an elastic band that is closing the bag.

2). The bow is attached to a pin that is holding the bag closed.

3). There is a drawstring inside the bag at the close. The bow is only attached to the top layer, not sewn through.

4). The maker attached little magnets inside the bag that keep it closed.

However, it is entirely possible that the particular image you shared is not meant to be opened. It could be a bag of potpourri, meant to look pretty and go in a sock drawer, but never to be opened.