• 千せん — thousand
• 数千すうせん — several thousand
• 千円せんえん — 1,000 yen
• 千人せんにん — a thousand people
• 千年せんねん — a thousand years
• 千羽鶴せんばづる — 1,000 paper cranes
• 千本桜せんぼんざくら — thousand cherry blossoms (song title or place name)

“千” is a core number kanji meaning one thousand. You’ll see it in money (千円), time (千年), and quantity words like 数千 (several thousand). In expressions, it can also suggest “a lot,” not only an exact count.