Barcelona is 1 hour behind Cairo
Best overlap: 9:00 AM to 6:00 PM in Cairo is 8:00 AM to 5:00 PM in Barcelona.
Shoot for 9:00 AM to 6:00 PM in Cairo; your Barcelona colleagues will see that as 8:00 AM to 5:00 PM. The overlap is wide at 9 hours, so you can protect mornings for deep work and still find plenty of meeting time.