Airbrake.monitor

You're seeing just the function monitor, go back to Airbrake module for more information.
Link to this function

monitor(pid_or_reg_name)

Monitor exceptions in the target process.

If you don't want system-wide monitoring, but would like to monitor one specific process, then you could use Airbrake.monitor/1

Examples:

With a given PID:

Airbrake.monitor(pid)

With a registered process:

Airbrake.monitor(Registered.Process.Name)

With spawn/1 and its counterparts:

spawn(fn ->
  :timer.sleep(500)
  String.upcase(nil)
end) |> Airbrake.monitor