just a quick question about why on the ME7.5 it has optimal ignition timing and also ignition timing maps
That doesn't have a quick answer; it is a complicated topic. Optimal timing is not used to generate actual timing; it is used as a reference to calculate torque efficiency.
The explanation of the latter term is not a noob question; you have some reading to do first.
and whats the variant 2...
Also doesn't have a quick answer; it depends on the context.
In the case of timing, variant is usually to reflect different cam timing.
In two point timing, the ECU will switch between the two maps depending on cam position
In variable timing, the ECU will interpolate between the two maps.