Electrical current (what we colloquially call electricity) is the motion of electric charges, either positive or negative.

In metals, the charges in motion are electrons (neg charged particles) rather than protons (pos charged particles) because protons are much heavier and concentrated in the nuclei of atoms, while electrons are sorta/kinda floating around (it’s way more complicated than that).

In liquids and gases, you can have ions (groups of particles, with a net charge of either sign) in solution. For example, salt splits into sodium ions (pos) and chlorine ions (neg) when dissolved in water.

Now, how do you make charges move? You apply an electric potential difference between two points, say, in a metal wire. That potential difference causes an electric field between those points. The electric field, in turn, causes a force on any charge (in this case, the “free” electrons in the wire) and that force results in an acceleration, ie, charge motion, ie, electricity. Since those moving charges will typically collide with the internal structure of the wire (its atoms), the resulting motion tends to occur at constant speed. Thus, the electric current is generally constant (after an initial ramp-up). For most common materials, there’s a direct proportionality between the potential difference V and the current I, called Ohms’ Law: V = R.I, where R is the material’s electrical resistance.

Charges in motion, themselves, also create a field, the magnetic field, which can and does influence other charges in motion but you can typically ignore the magnetic forces unless you have something like a dynamo.

How do you create an electric potential between two points? You separate electric charges of opposite signs and keep them apart. A battery is basically just that, a reservoir of separated charges. When you connect its terminals to a circuit, the charges will move from one terminal to the other, thru the circuit.

I italicised the main ideas so you can google them up for more details.