"Certaines personnes sont juste trop stupides pour comprendre ce qui est écrit dans les manuels."

Simplified Meaning:

Sometimes, people might not understand important instructions or guidelines because they lack the necessary knowledge or intelligence. Imagine trying to explain the rules of a complicated game like chess to someone who has never played it before. Even if the rules are written down clearly, that person might still struggle to get it. This idea can apply to many situations in life. For example, in a workplace, detailed procedures or strategies may be given to employees. But if some employees lack the basic understanding or skills, they might not follow them correctly. The quote suggests that comprehension isn't always guaranteed, even with clear instructions, because it's dependent on the person's ability to understand. To apply this in life, it's crucial to ensure that instructions are explained in ways that match the listener's skill level, or to provide additional training to those who need it.