That would include the Donetsk and Lugansk regions. Since there is chaos and military fighting in those two regions anyway... declaring Martial Law doesn't make any difference.
What does make a difference is that the rest of Ukraine is under Military control now. There is no assumption of "free speech". The military has a right to search and seizure of any property they deem necessary, including your car or house if they need it. You can be arrested and detained for anything the military wants to arrest you for... and be held for as long as they wish under Martial Law. The military can shut down any roads they want, take over any transportation they want, restrict or shut down radio stations, internet or cell phone services... .
In short, the SHTF in Ukraine. Anyone remaining there who doesn't want to be a part of "what comes next"... had better leave Ukraine pronto.
Link
Perhaps this speech by Putin is the reason for the martial law. In it he makes the case against the corruption in Ukraine, argues for the Russian heritage, and generally provides a rationale for the eastern portions secession from Ukraine. He's fomenting revolution and recognizing them as independent states.
Ukraine can't have talk like that spreading. Hence the martial law to shut down the speech.
https://www.youtube.com/watch?v=XTHUok0iQ-M