The image depicts the front of the Four Leaf fishpacking plant and its many laser tripwires. They must be triggered in the order shown to reveal the secret entrance to Marowski's chem lab. Companions can interrupt the activation sequence; instructing them to hold position is recommended.
This item cannot be dropped from inventory, even if one has completed Diamond City Blues. If the player wishes to remove this note from their character's inventory, on PC this can be done via the console commandplayer.removeitem 0004427a.