Parity: one flipped edge
Step 1 / 15
r2: Right inner layer: turn 180° (Written as TR2 in the textbook)
Only the top front edge is wrong: both its wings are flipped against the middle piece.
The wrong edge on top, at the front. It is the 4x4 OLL parity algorithm.
Step 1 of 15: r2. Right inner layer: turn 180°