simple question .For what are the marked values in the image down indicate to?
I mean / 1S/SGI OR 2S/SGI
with my thanks for all ..

thank u very muchThey indicate spatial stream count and if short guard interval or long guard interval is used. Which together with other factors like signal strength, channel width, and noise in your environment will affect at what rate the devices will operate - which MCS can be used. Note that the rate will increase while the link is in use, and while idle, the rate will drop.
https://en.wikipedia.org/wiki/IEEE_802. ... _and_speed