Contrary to what people may like to think, when someone dies owning property, it does not automatically pass on to their heirs. The first person to show up at the house with a pick up truck isn’t allowed to just take what they want. Your father’s classic car or his tools do not become yours simply because you remember him telling you that someday they would be yours.
Your grandma’s house doesn’t suddenly become yours just because her Will says she wants you to have it when she dies. Spoken words are fleeting and, unlike what is written down, fade with memories. A Will is just a set of instructions about what the writer wants down. It is not a transfer document. Once they are dead, something else has to be done before the property is yours. The estate has to go through a process before it is yours. The nature and extent of that process depends upon how much advance planning was done and how title was held before death.