FINIS TT Mode 1

How does this work? I'm looking at this Finis resource here Chart 1 on page 4 is sort of useful, but what does Chart 2 even mean? If you look at the left hand chart, of Chart 2, Mode 1 – the first row shows 20 seconds per stroke. Thatâ€s not even possible. You would sink if you took 20seconds to complete one stroke. So I donâ€t understand how to read any of those Chart 2 examples. CAn anyone help me please? Thanks