Wǒ de tóngshì xìng Cài míng Xián, shì gè cōngmíng nénggàn de rén.
My colleague's surname is Cai and given name Xian — he's a smart and capable person.
Tips
culture
蔡 is a relatively common Chinese surname (e.g., singer 蔡依林 Jolin Tsai, painter 蔡国强 Cai Guo-Qiang) and corresponds to the Korean surname 채 (Chae). The given name 贤 ('virtuous/wise') is auspicious and very common in both Chinese and Korean naming. In Chinese subtitle corpora 蔡贤 most often appears as a Korean character name.
memory
Both 蔡 and 贤 sit on common name-character lists. 蔡 (originally a feudal state 蔡国 in the Zhou dynasty) became a surname; 贤 ('virtuous, wise') is a top-tier name character — see also 圣贤 (shèngxián, sages and worthies).