保释金 is the money itself. The verb phrase for posting bail is 交保释金 (jiāo bǎoshìjīn). To be released on bail is 保释出狱 (bǎoshì chūyù).
culture
China's bail system (取保候审 qǔbǎo hòushěn) works differently from Western systems. 保释金 is more commonly encountered in translations of foreign news or legal dramas.