I was thinking recently that electrical wire carries electrons right that travel to the positron and push each other and get hot from the tension but since my house wires connect to a sub station where does the substation get all the electrons to send out... like a car battery too how does it start just from a battery full of liquid
where does the substation get all the electrons to send out
They are already in the wires.
Think about a wire that you run a magnet along. The moving magnetic field drags the electrons along inside the wire. That's all a power plant is, something turning a magnet beside a bunch of wire.
The electrons don't move all the way from the plant to you. When the magnet moves an electron from A to B, there's now two electrons at B. That extra force causes some other electron to move from B to C, which causes one at C to move to D. And so on, and so on...
It's like a water wave. The water isn't moving from the lake to you, it's just moving back and forth. It's the wave that's moving, or in the case of electrical power, the voltage.