The way to understand resistance is through Ohm's law, V = I * R. A given current made to flow through a resistor produces a voltage drop across the resistor: V = I / R. A voltage applied to a resistor causes a current to flow: I = V / R.
If you connect a battery directly to a motor rated for the battery voltage, the motor will spin. Now if you connect a resistor in series with the battery and motor, the motor will either not spin or spin more slowly. What the resistor has done is reduce the current flowing in the whole circuit (battery-resistor-motor) to less than that flowing in the circuit consisting of battery-motor only. Some of the battery voltage that was going to the motor is now across the resistor instead. So in this situation the resistor has reduced both the voltage across the motor and the current through it.
You could instead connect the resistor across the battery and motor. What this would do is dissipate some energy by drawing additional current from the battery (and heating the resistor), but if the battery could easily supply the additional current, the motor would continue normal operation, because it has the same voltage and current as before. (And with a fan blade added to the motor you'd have a hair dryer.)
I hope this gives you some insight into the relations of R, V and I.