When we go to the store to buy things, we usually make sure we are buying from a good store that sells good quality products. This is just like how businesses make sure they are buying things from good suppliers who sell good quality products.
So, supplier evaluation is like checking if the store (supplier) has good quality products, prices that are fair, and treats their customers (the business) well.
The business might look at things like how often the supplier has mistakes in their orders (like forgetting something or sending the wrong thing), or how long it takes for the supplier to send the things the business needs. The business might also look at how much money they have to pay the supplier, and compare that to how much other suppliers charge for the same things.
The business wants to make sure they are buying from a supplier that is reliable, trustworthy, and fits their needs. This way, they can make sure they are getting good quality products and the best value for their money.