What does this mean

The main base for your cordless phone has lost power - that's the big one with the answering machine. The base unit may have come unplugged, the AC adapter might have come unplugged, the outlet may have lost power, or there may be an issue with the power connector inside the base. Try another outlet or another adapter if the auxiliary phone bases use the same one. If you have a voltmeter, check that the adapter is putting out the output voltage specified on the adapter label.