Structure

Such a so-called DC motor is using the Lorence force to induce a Moment which turn the rotor inside the stator.
Inside the rotor are pairwise inserted copper wires which transport a current across it. This current crosses the magnetic field $\vec{B}$. This results in a force perpendicular towards $\vec{B}$ and the current $\vec{I}$.
The resulting force $\vec{F}$F can be described by the following cross product:

Right-hand rule

A good example for a better understanding of the Lorence force is the so called “right-hand-rule”. Take a look at your right hand. You don’t even need all your fingers lol.
Your thumb points the direction of the flowing current $I$. Your index finger points towards the direction the magnetic field directs. And your third finger, which you move 90 degrees from your hand, is now the direction of the resulting force $F$. Pretty simple huh?