If I see it correctly, there is no seal there. An adapter is screwed into the tap, to which the washing machine hose is then connected at the bottom. According to the arrows, the water flows through the adapter/tap connection. So 1.) carefully turn it to see if it is hand-tight. Then use a wrench to turn it a quarter to half a turn more, if it was not already tight. 2.) Unscrew the adapter, clean the threads of the adapter and the tap, check for damage. Then screw it back in with a little (small amount) of silicone sealing tape (as below) or hemp. Hand-tight plus a little turn with the wrench.
