The overall situation means: Luz, tell you your attitude towards knowledge and ignorance (that is, your attitude towards learning)! Knowing is knowing, and not knowing is not knowing. This is true wisdom.
The word "knowledge" in "knowledge also" leads to "wisdom" (meaning wisdom).
This is a famous saying of Confucius, which is used to remind people to treat knowledge with honesty and not to be hypocritical and proud. It is necessary to develop a down-to-earth and serious attitude towards learning, a style of seeking truth from facts, and avoid the habit of recklessness and vanity.
There is another explanation. In Professor Ceng Shiqiang's The Mystery of the Book of Changes, Professor Ceng Shiqiang means: I know one thing for those who know, but I don't know one thing for those who don't. My understanding is that different people have different answers. Professor Ceng Shiqiang gave an example of a student of Confucius betting with a grasshopper. The grasshopper says there are three seasons in a year, and Confucius' students say there are four seasons. Later, they asked Confucius together. Confucius looked at the grasshoppers and told them that there are three seasons in a year. After the grasshopper left, Confucius' students asked why. Confucius said that grasshoppers don't live in autumn, so for him, there are three seasons in a year, and there are still three seasons for you to fight with him. Therefore, "knowing is knowing, not knowing is not knowing" should mean "knowing some knowledge" with the purpose of "knowing this knowledge". (knowing is knowing), and the second half is the same.