Shares
Shares are little pieces of a company you can invest in (publicly traded). To own a piece of a company, you buy shares.
A share is like a single slice of a huge, delicious cake. The entire cake represents a company, and each slice (share) is a small part of that company. Just like slices can be big or small, shares can vary in size and value. When you buy a share, it's like you're buying a slice of this cake.
The better the cake (company) does, the more delicious and valuable your slice becomes. If the cake becomes popular and everyone wants a piece, your slice might become more sought-after, much like a share's value can increase when a company is doing well.