Ensure that your Brother printer is properly connected to your Mac. If it's a wireless printer, make sure it's connected to the same Wi-Fi network as your Mac.  Sometimes, simply restarting both your Mac and the printer can resolve connectivity issues. Turn off both devices, wait for a few minutes, and then turn them back on.  Go to "System Preferences" on your Mac, then select "Printers & Scanners." To know more about brother printer offline on mac . Check if your Brother printer is listed there. If it's listed as "offline," select the printer and click on the "Open Print Queue" button. Sometimes, clicking on "Resume" or "Reset Printing System" can help bring the printer back online.