The choice between "shoe" and "shoes" depends on whether you are referring to a single shoe or multiple shoes.
"Shoe" (singular): This form is used when referring to one individual shoe.
Example: "I need to buy a new shoe for my left foot."
In this example, "shoe" indicates that only one shoe is needed.
"Shoes" (plural): This form is used when referring to multiple shoes.
Example: "I have a collection of shoes in my closet."
Here, "shoes" implies that there are multiple pairs of shoes.
It's important to choose the appropriate form based on the number of shoes you are referring to in a given context.