This is an idiom that means they should pay attention. AT: "Listen carefully and remember" or "Do not forget this" (See: [[rc://en/ta/man/translate/figs-idiom]])
This can be stated with an active clause. Here "hands" refers to power or control. AT: "they will betray the Son of Man and put him in the control of men" (See: [[rc://en/ta/man/translate/figs-activepassive]] and [[rc://en/ta/man/translate/figs-metonymy]])
Jesus is speaking about himself in the third person. The word "hands" is a synecdoche for the people whose hands they are or a metonym for the power that uses those hands. You may need to make explicit who these men are. AT: "I, the Son of Man will be betrayed into the hands of men" or "The Son of Man will be betrayed into the power of his enemies" or "I, the Son of Man will be betrayed to my enemies" (See: [[rc://en/ta/man/translate/figs-123person]] and [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-explicit]])