This is a simple way to temporarily protect a new seedling or cutting from the elements. Use another pot to cover them, this way strong sunlight or heavy rain will not damage the plants. Slot in the pots gives some sunlight to get the seedling or cutting going while maintaining air circulation.
Pots are secured by using clips to ensure they are not blown away or toppled by heavy rain.
It is best to use hanging pots since they already has holes for wire attachment. Otherwise you will need to secure it either by making holes or different type of clips.
All done, good for a few week depending on type of plants that you grow in the pots.