I dont know what this means : J9 C9 D9 Z9 P9 R9 Y2 B1 M1 U1 H1 Q0 V0 W0 G0 S0 T0 L0 A0 K0
To me it means economy seats are available to purchase.
To me it means there is no positive space and no economy seats available. As CC and others have indicated above, they are selling seats they don't physically have in the economy cabin as they have empty seats in J (J means business class) that they can op-up pax into in the event they don't have the usual number of no shows.