This verse from Proverbs 17:28 is saying that even someone who isn't particularly intelligent can appear wise and discerning simply by keeping quiet. In other words, sometimes the best strategy is to say nothing at all.

Here's a breakdown of the meaning:

"Even a fool...": This establishes that the person being described isn't known for their wisdom or intelligence.
"...when he keeps silent...": This is the key action. The act of not speaking is what creates the impression.
"...is counted wise...": The consequence of being silent is that others may perceive this person as wise. They might assume the person is carefully considering their words, rather than having nothing of value to say.
"...when he shuts his lips, he is thought to be discerning.": This reinforces the same idea with slightly different phrasing. "Discerning" means having good judgment and understanding. By not speaking, the fool gives the impression of possessing these qualities.

In essence, the verse highlights the following points:

The power of silence: Sometimes, saying nothing is better than saying something foolish.
Perception vs. Reality: People often judge based on appearances. Silence can create an illusion of wisdom, even if the underlying intelligence isn't there.
Self-control: Knowing when to remain silent is a form of wisdom in itself. It demonstrates self-control and an awareness of one's limitations.

Practical implications:

Think before you speak: Consider whether your words will add value to the conversation or whether it's better to listen and learn.
Avoid speaking out of ignorance: If you don't know much about a topic, it's often wiser to remain silent than to reveal your lack of knowledge.
Be a good listener: Listening attentively can make you appear more discerning and thoughtful.
Don't feel pressured to always have an answer: It's okay to admit that you don't know something.

In conclusion, Proverbs 17:28 serves as a reminder that sometimes the most intelligent thing you can do is to simply keep quiet and listen.