What those figures mean, as it currently stands, is that BA have for sale 9 or more 'J' bucket seats in Club World (Business class), 9 or more 'W' bucket seat in Premium Economy and 9 or more 'Y' bucket seats in EuroTraveller (Economy). Note that these fare buckets are the most expensive for each class of travel.

All the cheaper fare buckets i.e. in Club World (from cheapest to dearest) I,R,D & C are currently zero - so none of these fare buckets are currently on sale (or they may already have been sold, or only some sold).Likewise with the cheaper T & E fare buckets in Premium Economy and the G,N,O,Q,S,V,L,M,K,H & B fare buckets in EuroTraveller).

Whether or not BA may release cheaper fare bucket seats for sale at some point is a secret probably only known to revenue management. As your proposed flights are some distance away it may change. However, MBJ is probably a popular destination at that time of year - over Christmas and also for getting away from the depths of UK winter, so they maybe able to sell them at the more expensive bucket fares.