The M is metric, the g8 is the tolerance; there are tables for that.
It may be that this case is -0.005 to -0.027 mm from nominal, however MX *such as M8* is usually a thread designation. If that is the case then the g8 is incorrect as thread tolerances have their range as a prefix, such as M8-8g6g.
The others are surface roughness limit symbols. Rz is the average maximum peak to valley of five consecutive sampling lengths within the measuring length. The small horizontal line on the roughness check mark indicated that material is required to be removed to reach the final dimension.
I don't know why the one symbol has parentheses around it.
I also don't know why the 90 degree symbol/dimension is there.