Welcome to the forum! I can tell you that a lesion is a change in the structure of a persons brain or any organ do to injury or medical condition.
The grey and white matter they are talking about is an area that is protecting you brain from being injured called the cerebal cortex and this is the area of your brain where they have possibly found scar tissue or brain damage from the stroke or other medical issues.
I will tell you that the best thing for you to do is to see an Epileptologist instead of a neuro. because these Drs. know much more about epilepsy and how the brain works. I've had epilepsy for 40 yrs. and after seeing many different neuros. I got the best help from an Epileptologist this Dr. can also help you with your stroke and any other neurology problems you might have. Try taking vitamin B12 1000 mcg. once a day this will help calm the nerves, cut back on caffeine, starch foods and carbs because this will trigger seizures for some people. To see an Epileptologist you have to go to a University hospital or a very large hospital. You can have your family Dr. refer you to one if you want to see one. Also have them do a DNA test on you this will show what meds will help you the most with the least side effects. I wish you only the best and May God Bless You!