长青 is a literary adjective meaning 'evergreen' or 'enduring'. It combines 长 (long) and 青 (green) and is used poetically for trees that stay green year-round or metaphorically for lasting friendships, traditions, or spirits. You'll most often encounter it in formal or written language, not everyday speech. The standard pronunciation is cháng qīng (two syllables), though the source data lists the pinyin for this row as just cháng, which appears to be an error.