Tā zài gōngdì dāng bāogōngtóu, shǒuxià yǒu èrshí duō rén.
He works as a labor contractor at the site, with more than twenty people under him.
Tips
culture
包工头 is a recurring figure in Chinese news about migrant workers (农民工 nóngmíngōng) and unpaid wages — the contractor takes a project, hires day laborers, and is often blamed for withholding pay around Chinese New Year.
memory
Parse it as 包 (to take on / contract) + 工 (work) + 头 (head/leader): 'the head guy who contracts the work'.