substitution
noun [ C or U ] uk/ˌsʌb.stɪˈtʃuː.ʃən/ us/ˌsʌb.stəˈtuː.ʃən/
C1 换人
the use of one person or thing instead of another
It looks as though the coach is going to make a substitution (= change one player for another in the game). 教练似乎要换人。