If someone or something is impaled, a sharp pointed object goes through them — a spike, a spear, a fence post, a metal rod. The picture is always the same: a point goes in, and often comes out the other side. It is a violent, physical word. In history it names a cruel way of killing people. In modern English it is still used for accidents (“he was impaled on the railings”) and, much more lightly, for food (“impale the marshmallows on a stick”). The food use is real, but the word itself is not a joke unless you are clearly talking about fruit or snacks. You will also hear it in news and hospital reports. Most everyday speakers would just say “a spike went through him.” The verb is often passive: we say someone was impaled on something, more than they impaled themselves.