Hello SweetTasha,
Welcome to the Microsoft Community.
The "Desktop PIN" you're seeing on your Surface Book (SB) is a security feature used during the process of pairing devices in Windows, typically via Bluetooth. When you try to connect your Surface Book to another device, both devices will display a PIN (Personal Identification Number). This PIN is used to ensure that the correct devices are being paired and to prevent unauthorized connections.
Based on your image, we guess you are trying to connect your Surface Book with another PC. We recommend you check the PIN displayed on your Surface Book and compare it with the PIN shown on the device you're trying to connect. If the PINs match, it means the devices recognize each other and you can proceed with the connection. What you need to do next is just to click the "Connect" button on your Surface Book to complete the pairing process.
The PIN code can appear in several different situations. In addition to your current situation, it can sometimes appear when the device you are trying to pair with does not have a screen, such as a keyboard. Connecting to some keyboards might require you to enter the PIN using that keyboard. However, for other types of devices that do not have an input method, you just need to click Connect.
If you need any further assistance, please let us know and we will provide more advice.
Best Regards,
William.Y | Microsoft Community Support Specialist