The SPL readings show you how loud a speaker sounds when given 1 watt of power. The measurements were taken with a microphone placed 1 meter away from the speakers.
The anechoic reading is taken in a specially designed chamber that absorbs all echoes. The other reading shows how the speaker would likely perform in any given normal room (where echoes add to its overall perceived volume).
For the frequency response, the two tests show you readings taken with different accuracy levels. For the M22ti, for example, the speaker can repoduce sound from 22kHz down to 60 Hz without going deviating more than 3 db in SPL. If you look at the second measurement, the db range is larger (from -9 to +3), so the range the speaker can reproduce is also larger (22kHz to 50Hz). The reading shows that at 50Hz the sound is as much as 9 db softer than at 60Hz.
