Exactly two people
Meet the dual: you two and they two, with clear gender cues.
The idea
Modern Standard Arabic has special forms for exactly two. Antumaa takes -tumaa, for any gender. Humaa takes -aa for two males or a mixed pair, and -ataa for two females. Humaa is spelled the same for both genders, so read the English cue. There is no separate dual I/we form: naḥnu already includes two speakers.
كَتَبَ
kataba — he wrote
antumaa — you two (any gender)
-tumaa addresses exactly two people of any gender.
كَتَبْتُمَا
katabtumaa — you two (any gender) wrote
humaa — they two (male or mixed pair)
-aa marks two males or a mixed pair. Hold the final aa.
كَتَبَا
katabaa — they two (male or mixed pair) wrote
humaa — they two (female pair)
-ataa marks exactly two females. Humaa alone does not tell you their gender; use the meaning given.
كَتَبَتَا
katabataa — they two (female pair) wrote