买通 is a resultative verb (r.v.) meaning 'to bribe someone into cooperating, especially to gain access or favor'. The second character 通 ('through') indicates the result: the bribe succeeds in 'opening a path'. Unlike the more formal 贿赂 (huìlù), 买通 is colloquial and implies a specific goal (e.g., getting past a guard). It can be used in potential complement patterns: 买得通 (able to bribe successfully) and 买不通 (unable to bribe).