Is a focal motor seizure serious like a convulsion?

Yes: It can be even more serious if the affected brain area extends further and involves more functional capacity. One would need to investigate why any seizures are happening at all -- to be sure there are no masses or vascular issues causing them, etc. Level of consciousness during seizures is important, as some "partial" seizures can become "complex", and would then include loss of consciousness.

Very likely: A focal motor seizure is a type of convulsion.

Yes: A true focal motor seizure is a sign of a local irritable brain lesion, which could be an area of trauma, bleeding, infarction, tumor, infection. Often these focal problems generalize and cause a full blown grand mal seizure. If you are experiencing such spells, start an anti-epileptic medication.

Yes: A focal motor seizure is potentially serious, since it means there is a localized area of brain that is resonsible. It requires an evaluation with neuroimaging to evaluate for structural abnormalities, tumors, blood vessel malformations or bleeding within the brain.