What does this traffic sign combination indicate?

You are correct. This sign combination means that a stop sign is coming up in 100 meters, and you will have to stop and give way there. The top sign alone means "give way," but with the additional sign below stating "STOP 100 m," you are being warned in advance that a mandatory stop is required shortly ahead. This combination helps you prepare to come to a complete stop, not just yield. In the theory test, always pay attention to these combinations, as the additional sign can change the rule described by the main sign.