A knowledge panel is Google's summary card about you, assembled without asking your permission. You do not write it directly, but you can absolutely influence what goes in it.
The short version
A knowledge panel is the information box that appears in search results for a recognised person, brand, organisation, or thing. Google builds it automatically from sources it trusts, such as its Knowledge Graph.
How to influence it
Keep your entity information consistent across the web
Earn mentions on authoritative sources Google trusts
Use structured data to clarify who and what you are
Claim and verify your panel where Google allows it
FAQ
Can I edit my knowledge panel?
Not freely. If you verify your representation with Google, you can suggest changes, but Google controls the final content based on its sources.