It sounds like your grandmother had experienced a type of stroke, known as Hypertensive intracerebral hemorrhage (bleeding in the brain due to high blood pressure).
Brain tissue swelling and bleeding within the brain put increased pressure on the brain and can eventually destroy it.
Difficulty speaking or understanding others, difficulty moving any body part and many others are symptoms of brain damage.
How well a person does depends on the size and location of the bleed.
Recovery can occur completely, or there may be some level of permanent loss of brain function ( permanent loss of any brain function, seizures).