What does a resistor do?
Electric flow is the motion of electrical charges through a material. Resistance is the physical obstruction of these moving charges.
A certain amount of energy is required to keep these charges in motion, and since the energy drop is proportional to the amount of charge kept in motion, this results in a voltage drop across the material since electromotive force (in volts) is energy (in joules) per charge (in coulombs).
Since it is a physical obstruction, it also restricts the rate at which charges can move across a given point per unit time. This results in a maximum current, since current (in amperes) is charges (in coulombs) per unit time (in seconds).
And as it turns out, if you apply more or less electromotive force across the same resistance, the current increases or decreases exactly linearly. This gives rise to Ohm's Law, which states that electromotive force is proportional to the product of current and resistance, that is, \$E = IR\$.
It can be helpful to think of voltage as the pressure or force that is propelling the electrons through the pipe that is the wire. Current is the number or amount of electrons passing a given point at any one time. Resistors do just what their name says; they resist. You can use them to limit either current or voltage, depending upon whether they are wired in series (one after the other), or parallel (sharing the same connection points, side-by-side. Think of electrons as ping pong balls passing through a tube, push one in and the ones already inside push one out the other end.Doubling the length of the tube (series wiring a resistor) increases the force needed to push it through, so it limits voltage. However, if you put the tubes side-by-side, then the same number of balls have to go through twice as many paths, limiting how many can go at once, and thus limiting current. I know this is grossly oversimplified and does not account for all situations, but it can give your mind's eye a visual representation of the theory of electron flow and how resistors can affect such.
Hopefully this is simple enough:
Voltage arises from the potential energy in separation of charges (one node is positive with less electrons, one node is negative with more electrons). Think about it like having a bowling ball (charge) on the ground, versus at the top of a ladder. The ball at the top of the ladder has more potential energy, more voltage.
Current arises from the "flow" of charge.
Resistors let you choose how much current flows for a given voltage since you can think of wires as having no resistance (simplified).
In short: Resistors limit the flow of electrons, reducing current. Voltage comes about by the potential energy difference across the resistor.