What Does The Word Resistance Mean In A Electric?

In a light bulb, the small piece of tungsten (or whatever they use nowadays) between the two wires of the circuit constitutes the resistance.  High resistance creates heat and in this case light.
If a good conductor such as copper is put in to replace the tungsten, an immediate short circuit would occur because there is very low resistance.
The basic formula is Voltage equals Amperage times Resistance.
Resistance refers to the conductor's tendency to give up electrons.  Good conductors are low resistance (to giving up electrons) while bad conductors give up electrons reluctantly and are therefore high resistance.