• 髪かみ — hair (on the head)
• 髪型かみがた — hairstyle
• 髪の毛かみのけ — a strand of hair / hair (more literally “hair-hair”)
• 長髪ちょうはつ — long hair
• 白髪しらが — gray / white hair
• 金髪きんぱつ — blond hair
• 洗髪せんぱつ — hair washing / shampooing

The top of 髪 is the radical 髟（かみがしら） — it shows long hair hanging down. This radical almost always signals “hair.” The lower part gives sound (ハツ). Put together, 髪 simply means “hair on the head,” the hair you comb, wash, and style.