Here the word "slave" is a metaphor. This implies that "sin" is like a master for the one who sins. AT: "is like a slave to sin" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This is an ellipsis. You may translate it by including the implied words. AT: "the son is a member of the family forever" (See: [[rc://en/ta/man/translate/figs-ellipsis]])
# if the Son sets you free, you will be truly free
It is implied that Jesus is talking about freedom from sin, which is a metaphor for being able not to sin. AT: "if the Son msets you free, you will truly be able to refrain from sin" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-metaphor]])
"Son" is an important title for Jesus, the Son of God. Jesus was speaking about himself. AT: "If I, the Son, set you free" (See: [[rc://en/ta/man/translate/guidelines-sonofgodprinciples]] and [[rc://en/ta/man/translate/figs-123person]])