Here "the days" stands for a period of time. And, "flesh" stand for Jesus's earthly life. Alternate translation: "While he lived on earth" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Possible meanings are 1) God was able to save Christ so that he would not die. Alternate translation: 'to save him from dying" or 2) God was able to save Christ after Christ's death by making him alive again. If possible, translate this in a way that allows both interpretations.