It depends on the objects (somebody or something) For saying somebody like "yourself" it is 'Bao Zheng Ni Zi Ji De An Quan' = 'keep yourself safe' For saying something like "your wallet" it is ‘Bao Guan Hao Ni De Qian Bao’ = 'keep your wallet secure' Hope it helps :)

意思是 保证...的安全 for example “ keep yourself safe ”means “保证你自己的安全”