。
He was headhunted by a rival company.
Literal
He [topic-は] rival company [by-に] was-pulled-out.
引き抜く is a compound verb literally 'pull out' used figuratively for 'to headhunt, to poach (an employee from another company).' In the passive 引き抜かれる, the employee becomes the topic/experiencer of being poached, and に marks the agent (the rival company doing the poaching). ライバル is a loanword used in business contexts for 'rival company/competitor,' often more neutrally than the English 'rival' (which can imply hostility).