I know the magenta arrow is the T/D (top of decent) but what does the blue one represent closer to approach?

If I am not mistaken it represents where it is calculated you will reach the current altitude sett in the autopilot.

>If I am not mistaken it represents where it is calculated you>will reach the current altitude sett in the autopilot.That's correct.To be more precise, where the FCP altitude will be reached (in PROF mode the active autopilot target might be different than the FCP altitude, due to altitiude restrictions).Applies bot to climb and descend.