The description contains detailed diagrams and links to the video. In the video, you can see how each element is crocheted.
You can knit a brooch with yarn 500m / 100g, a hook 1.1-1.3 mm. Then its size will be 10-11 cm.
If you crochet it with yarn 2000m / 100g, the hook is 0.55-0.65 mm, then the size of the brooch will be 5 - 5.5 cm.
It is better to use 100% acrylic or 100% polyester.