Brussels Airlines has a long tradition of flying to the Sub-Saharan Western Africa. This sale is based on codeshares on their partners United Airlines or Lufthansa and tag-on flights with fares for around 2100, significantly below the ~4000 with Brussels flight numbers. Stopovers are allowed for free so you could in theory use this a USA to Europe flight, with a SIGNFICANT detour. This sale seems to not work to one-stops so you need to go the Second Tag destinations and Stopovers are not seeming allowed in those first stops.
These fares book into P class so earnings are stable in the 100% range to most Star Alliance airlines, here are some highlights from the fare rules.
TRAVEL FROM TURNAROUND MUST COMMENCE NO EARLIER THAN THE FIRST SUN AFTER ARRIVAL AT TURNAROUND OR - TRAVEL FROM INBOUND TRANSATLANTIC SECTOR MUST COMMENCE NO EARLIER THAN 7 DAYS AFTER DEPARTURE OF THE OUTBOUND TRANSATLANTIC SECTOR.
TRAVEL FROM LAST STOPOVER MUST COMMENCE NO LATER THAN 3 MONTHS AFTER DEPARTURE FROM FARE ORIGIN.
2 FREE STOPOVERS PERMITTED ON THE PRICING UNIT - 1 IN EACH DIRECTION IN FRA/MUC/GVA/VIE/ZRH/BRU/BER/DUS/LIS/OPO/ REK/PDL.