In Issac Newton's first law of motion, he says an object in motion will stay in motion until acted upon by an external force, and an object at rest will remain at rest.
Inertia is the resistance to motion of an object touching another. With the law of inertia always in play, you cannot pass through solid objects like walls or tables.
In the photo above, my finger will not pass through the table because it has inertia which resists the force of my finger.
Even after running I cannot break the wall and the law of inertia