Video: view
You shake something when you move it vigorously up and down or from side to side. The dog in the photo is shaking water out of its coat. People shake drinks like milk to make them frothy.
Shaking can be used to communciate too. People shake their heads from side to side to mean "no", and two people will shake hands as a greeting.
Scientific name: allium oschaninii
Sharing is when you take something and you break it up so several people can have some too. You can share time as well as things like food. The two women in the picture are sharing a pizza.