The last six edges

There are 6 edges left: the 4 on top and the 2 in the M slice (front and back on the bottom). You only use M and U now.

First, orient the edges: an edge is oriented when its top or bottom color faces up or down. M’ U M flips 4 edges at once: the two in front (top and bottom), and the left and right ones on top.

Next, place the left and right top edges (UL and UR), by bringing them together to the bottom and then lifting them up with M2.

Finally, the last 4 edges are solved in the M slice: one or two M2 and U2 are often enough. It’s the same idea as the Ua, Ub and H PLLs.

Remember: This step only takes two different moves: with practice, it gets very fast.

Troubleshooting

I can’t orient the edges

Count the misoriented edges: there’s always an even number. With 4 edges, put them front-top, front-bottom, and left and right on top, then M’ U M.

The centers aren’t lined up at the end

Do M or M2 to put the top center back on top.