The component $D2$ in your project is a diode with the part number $NUP2105L$. This device is typically used for Electrostatic Discharge (ESD) protection and other transient voltage suppression scenarios.

In your schematic, $D2$ is connected:

The configuration positions $D2$ to protect the CAN bus differential signal lines (CANH and CANL) from voltage spikes or static discharge by clamping excess voltage to ground.