The Arabic term «al-jamʿ bayna al-naqīḍayn» is about the law of contradiction. The law of contradiction means that two antithetical propositions cannot both be true at the same time.
So for example: Zayd cannot be inside his house and outside of his house at the same time.
Source:
https://youtu.be/TWLDM9BNdAg
Translation by Navid Chizari