half a clog somewhere past where the dishwasher and sink drains meet up. potential options to try:
you can try letting it fill with water a bit then plunging with toilet plunger
pour some baking soda and vinegar in there
drain snake
drano
here this might be helpful to someone - lots of people use toilet plungers wrong
dont try to push water/air in with the plunger, try to slowly push in to create a watertight seal and then wiggle the plunger back and forth in a jerk off motion to move all the water back and forth and break the jam