Every Arabic noun is either masculine or feminine. A masculine noun refers to a masculine person or thing, like «ولد» (boy), «قلم» (pen), «كتاب» (book). A feminine noun refers to a feminine person or thing, like «بنت» (girl), «وردة» (rose), «شمس» (sun).
The most common feminine marker is the tied ta' (ة) at the end of a word: «معلّم» (male teacher) becomes «معلّمة» (female teacher), «طالب» becomes «طالبة», «كبير» becomes «كبيرة». But watch out: some nouns are feminine without any ending marker, like «شمس» (sun), «أرض» (earth), «يد» (hand), «ريح» (wind) — these are called “figuratively feminine.”
Knowing a noun's gender matters because it changes the form of any adjective describing it: we say “a tall boy” (ولدٌ طويلٌ) but “a tall girl” (بنتٌ طويلةٌ).
