As for you
God uses this phrase to introduce what Abram would have to do as part of God's covenant with him.
keep my covenant
"observe my covenant" or "honor my covenant" or "obey my covenant"
This is my covenant
"This is a requirement of my covenant" or "This is part of my covenant." This sentence introduces the part of the covenant that Abram must do.
Every male among you must be circumcised
This can be stated in an active form. AT: "You must circumcise every male among you" (See: rc://en/ta/man/translate/figs-activepassive)
This refers to human males.
You must be circumcised in the flesh of your foreskin
Some communities may prefer a less descriptive expression such as "You must be circumcised." If your translation of "be circumcised" already includes the word for "foreskin", you do not need to repeat it. This can be made active. AT: "You must circumcise every male among you" (See: rc://en/ta/man/translate/figs-euphemism and rc://en/ta/man/translate/figs-activepassive)
the sign of the covenant
"the sign that shows that the covenant exists"
Possible meanings are 1) "the sign" or 2) "a sign." The first means that there was one sign, and the second means that there may have been more than one sign. Here the word "sign" means a reminder of something that God had promised.