It's not always possible to do time-consuming hand-sewn repairs, so iron-on patches can be just the thing for a quick fix for a hole or a stain.
These iron-on patches come in pairs. The smallest patch measures approximately 2.5 cm in height and approximately 3.5 cm in width. The large one measures approximately 3.5 cm in height and approximately 5 cm in width.
Although they can be ironed on as they are, I recommend also sewing them if you have the opportunity, as it will be much more durable. It's easiest with a machine since the iron-on patches are stiff, and it might be worthwhile to use a darning foot if you have one, and then remove the feed dogs, so you can move the fabric/garment in any direction you want. Feel free to practice on a fabric scrap with a ballpoint pen drawing of a heart or star or something. The stitches don't have to be perfectly even, the most important thing is that the patch is securely attached :)
Iron-on patches are a bit stiff, so if it's a very large worn area with a small hole, I recommend first attaching a reinforcement patch to the inside of the garment, either with machine stitching (a bit of a quilt style with stripes or checks, perhaps with thread that matches the garment?) or by using a fabric patch and fusible web, and ironing it on the inside, and then covering the hole or stain with the flower. Of course, you can also use iron-on patches to decorate clothes that don't yet have any damage or wear :)
Reinforcing worn areas from the inside is a good idea so you don't get a new hole right at the edge of the iron-on patch, where there will be extra stress with the hard against the thin/worn fabric.