Why does a voltmeter show voltage drop
V1, R1, and LAMP1 are connected in parallel in your circuit.  That means that the voltage across R1 is equal to V1 or 12 volts.  Likewise, the voltage across LAMP1 is also equal to V1 or 12 volts.  Thus the current through R1 is 12 volts/100 ohms or 120 milliamperes.  The current through LAMP1 is 12 volts/100 ohms or also 120 milliamperes. Note that the current through R1 is the same as the current through LAMP1 because their resistance is the same, not because they are connected in parallel. In a practical circuit, the interconnecting wires would have some small resistance (small compared to 100 ohms) so that the voltage across R1 would be slightly less than V1.  The voltage across LAMP1 would also be slightly less than R1 due to the voltage drop in the wires between R1 and LAMP1.