Witch balls are hung in windows by those who wished to keep witches away. It was said that the beauty of the balls would attract evil spirits and trap them. Nowadays, they're used by witches to ward against negativity and harm.
They are typically spheres of glass that may be painted or decorated. They may be filled with herbs or twigs. They can be placed in windows, rest on pillows, hung from hooks inside and around the house, lay in gardens, or whatever you want.
How to make one:
You can use a glass ornament, old lightbulb, whatever you want.
Fill it with herbs, crystals, and anything else you want, preferably ones that match your intentions.
Place it wherever you want.