Prague is 1 hour behind Johannesburg
Best overlap: 9:00 AM to 6:00 PM in Johannesburg is 8:00 AM to 5:00 PM in Prague.
Johannesburg and Prague overlap from 9:00 AM to 6:00 PM (Johannesburg) to the equivalent 8:00 AM to 5:00 PM in Prague — that's your meeting window. Plenty of room to work with: 9 hours of daily overlap means you can prioritise people's preferences over the clock. Note the seasonal wrinkle: when Prague is on daylight saving and Johannesburg isn't, the gap between them grows or shrinks by an hour.