O.W.L.s (Ordinary Wizarding Levels) and N.E.W.T.s (Nastily Exhausting Wizarding Tests) are administered in the fifth and seventh years to Hogwarts students, and a student's grade on those tests determines what jobs students can apply for and hold as adults. The tests’ existence encapsulates the Ministry's vision of what a good, proper future looks like for students: no matter what particular job a student chooses, it's one that's Ministry-approved. However, several characters, including Fred, George, and Harry, show through their actions that these standardized tests are only one way to measure success and in actuality, they don't reveal anything especially useful about students. Despite Fred and George's three passing O.W.L.s each, they still manage to develop compelling joke products and open a shop, proof that while school itself was useful for them, the tests were entirely useless. Harry, though he's a middling student, is also very successful fighting Voldemort in the real world despite not even having scores yet. Through Fred, George, and Harry's experiences, the novel suggests that the O.W.L.s and N.E.W.T.s actually represent the closed-mindedness of the Ministry, its desire to control the population by dictating young people's futures, and its unwillingness to look at people as multifaceted individuals.
O.W.L.s and N.E.W.T.s Quotes in Harry Potter and the Order of the Phoenix
"You know, I don't get why Fred and George only got three O.W.L.s each," said Harry, watching as Fred, George, and Lee collected gold from the eager crowd. "They really know their stuff..."