What does "a knowledge agent," mean? Could you explain?
It is hard for us humans to separate information from meaning because we cannot help interpreting messages. We infuse messages with meaning automatically, fooling ourselves in into believing that the meaning of a message is carried in the message. But it is not. This is only an illusion. Meaning is derived from context and prior knowledge. Meaning is the interpretation that a knowledge agent, such as a human, gives to a message. It is different from the physical order that carries the message, and different from the message itself. Meaning emerges when a message reaches a life-form or a machine with the ability to process information. It is not carried in the blots of ink, sound waves, beams of light, or electric pulses that transmit information.

Question

What does "a knowledge agent," mean? Could you explain?
It is hard for us humans to separate information from meaning because we cannot help interpreting messages. We infuse messages with meaning automatically, fooling ourselves in into believing that the meaning of a message is carried in the message. But it is not. This is only an illusion. Meaning is derived from context and prior knowledge. Meaning is the interpretation that a knowledge agent, such as a human, gives to a message. It is different from the physical order that carries the message, and different from the message itself. Meaning emerges when a message reaches a life-form or a machine with the ability to process information. It is not carried in the blots of ink, sound waves, beams of light, or electric pulses  that transmit information.

Answer

"knowledge agent" is a rare expression that someone might used when teaching specific details about something.

Meaning is the interpretation that a knowledge agent, such as a human, gives to a message. It is different from the physical order that carries the message, and different from the message itself.

I think what they are trying to say is that there are three parts to a message: the message itself, the message carrier and the message interpretation. They are specifically referring to an "agent" so that you can see it is different from the carrier and the message itself. The "agent" here is the thing (a person in this case) that gives meaning to the message.

Sorry, it's complicated and hard to explain in simple language.