OnTriggerEnter

void OnTriggerEnter(Collider other) runs once, on the physics step when another collider starts to overlap a trigger. other is that collider, so other.name, other.gameObject and other.CompareTag("Player") tell you what came in. Unity calls it on the scripts of both objects: on the trigger, other is the visitor, and on the visitor, other is the trigger.

This finish line reacts to the player and to nothing else, so a ball that rolls across it logs nothing:

void OnTriggerEnter(Collider other)
{
    if (other.CompareTag("Player"))
    {
        Debug.Log(other.name + " crossed the finish line");
    }
}

The parameter must be a Collider. Written as void OnTriggerEnter(Collision collision), the script still compiles, because to C# it is an ordinary method. Unity checks the parameter itself, logs a Script error: OnTriggerEnter that says This message parameter has to be of type: Collider, and never calls the method. Collision belongs to OnCollisionEnter, where two solid bodies meet at a contact point. A trigger has no contact to report, only the collider, so it gets a Collider.