Magnetic field can pass through non-magnetic material like aluminium, copper, paper, etc. However, if you place a magnet on one side of a magnetic substance such as iron, the field on the opposite side is weak. This phenomenon is called magnetic shielding.
a bar magnet, a pin, thread, clamp, a sheet of iron, pieces of non-magnetic material like paper etc.
Suspend a bar magnet from a clamp. Tie a pin to one end of a string. Stick the tip of the pin to the magnet. Hold the portion of the hanging string close to the ground and slightly pull it. The pin will be detached from the magnet but will be floating in the air due to attraction from the magnet. Now, bring a paper in the space between the pin and magnet. The pin does not fall. Now, bring iron foil in between. The pin will fall this time.
In non-magnetic material, the magnetic field penetrates through the material and appears on the other side. But when iron foil is in between, the safety pin falls immediately, means the iron foil has shielded the magnetic field and field on the side of it become weak.