To standardize something is to make it fit a certain guideline or requirement. If a school decides to standardize its grading system, it makes sure every teacher gives grades in exactly the same way.
Use the verb standardize to describe what an organization or company does when it makes a product or rule conform to a certain model. Often, to standardize things is to make them all exactly the same. When a city standardizes all its playground equipment, every park begins to look alike, with the same slides, swings, and sandboxes.