SPNEGO stands for "Simple and Protected GSSAPI Negotiation Mechanism". It is a way for computers to talk to each other securely so that they can share information without anyone else seeing it.
Think of it like a secret handshake between two friends. If you and your friend want to communicate something important, you might come up with a special handshake that only the two of you know. That way, if someone else tries to join in the conversation, you can tell that they don't know the secret handshake and that they're not really your friend.
In the same way, computers use SPNEGO to establish a secure connection between them before sharing any information. They do this by sending messages back and forth that only they can understand. This makes it much harder for outsiders to intercept the messages and figure out what's being said.
Overall, SPNEGO helps keep important data safe and is used in many different types of computer networks, such as in businesses and governments.