"He has a small bedroom."
Translation:عِنْدهُ غُرْفة نَوْم صَغيرة.
It is related to the grammar actually, whether the compound of the two nouns are defined or not. Treat the two words as one entity.
- THE bedroom: غرفة النوم (ğurfat-ul-nawm).
- A bedroom: غرفة نوم (ğurfatu nawm).
In such Genitive compounds, when the compound is to be defined, the definite article (AL) is added to the second word in the compound. In the case of more than 2 words forming a Genitive relation together, then (AL) is just added to the last word in the compound.