what unit is the "M" of 0.2M in the colorbar of the legend on the right of the Fermi chart? How to convert to m/s?

IFermi
1

When the Fermi velocity is projected onto the Fermi surface using a coloring scheme, the Fermi velocity shown in the legend on the right side is 0.2M,1M, etc. What does the unit “M” here represent? How to convert to m/s? Please help me. Thank you