When someone says they "don't suffer fools gladly," it means that they have little patience or tolerance for dealing with people they consider foolish, unintelligent, or lacking common sense. In other words, they have a low tolerance for interacting with individuals they perceive as being foolish or displaying foolish behavior.
This phrase suggests that the person values intelligence, competence, and practicality, and they prefer to surround themselves with people who possess these qualities. They may find it frustrating or irritating to engage with individuals who they believe lack critical thinking, make foolish decisions, or demonstrate a lack of understanding.
Someone who doesn't suffer fools gladly is likely to be direct and straightforward in their communication, may not indulge in small talk or idle chatter, and might be quick to dismiss or avoid interactions with individuals they deem as "foolish."
It's important to note that this phrase can be subjective, and what one person considers foolish behavior might not be the same for someone else. People's perceptions of intelligence and foolishness can vary significantly based on their values, experiences, and cultural backgrounds.