How it works
The bottom row is the row just below the home row. It has seven letters: z, x, c, v, b, n and m.
Think of the keyboard as a house with floors: home is the middle floor, the top row is upstairs and the bottom row is downstairs.
One finger curls down to a bottom row key, taps it, and comes straight back home. Only that finger moves.
Keep your wrist still, and a still hand always knows where home is.