This is a "red-fleshed apple"

Pink Pearl apples are generally medium sized, with a conical shape. They are named for the color of their flesh, which is a bright rosy pink sometimes streaked or mottled with white. They have a translucent, yellow-green skin, and a crisp, juicy flesh with tart to sweet-tart taste. Pink Pearl apples ripen in late August to mid-September. It is susceptible to scab, and the fruit tend not to keep well on the tree once ripe.

Via Winelandia and The Soul is Bone.