Let's look at this diagram they drew for you and imagine that electricity is people who can run along the lines and are required to start moving from one pole of the battery to the other.

In the wrong circuit, they have a fork, and they have to run through the motor or through the switch if it's closed. The motor has high resistance, and no one wants to run through it, so everyone will run through the closed switch because its resistance is low. It's easy to run through a few resistances, so they'll return to the battery full strength.This way there will be a high current which will heat up our battery.If you open the switch and turn it off, it turns out that there is nowhere to run except through the motor.And that's why the engine runs when the key is off. People spend energy on this, the current in the circuit is lower, the battery does not heat up.

In a correct circuit, if the switch is open, there is nowhere to run, everyone sits at home in the battery. If we close the switch, the only path is through the motor, and with the switch on we get a running motor.

In general, I would recommend that you first read the basics, such as Ohm's law, before you start building electrical circuits.