We are allowed. Most of them are definitions which can be Googled anyway. The definitions won't make much sense without the necessary background knowledge though so I was just trying to gauge how much the OP knows before giving them. I may as well give a list now, since potential is the main concept that needs to be known. We're allowed to give answers to calculation questions too, but only as a last resort.
1. The difference between the potentials at two points.
2. The potential difference between the terminals(of a cell/battery). It's the actual potential supplied by the battery to the circuit. It's often denoted by r. In a real battery, this is smaller than the emf(when discharging).
3. As above.
4. The resistance within the battery due to the materials of the battery. It decreases the terminal voltage. In many cases it's assumed to be negligible.
5. The potential supplied to electrons as they pass through the cell/battery. It's usually denoted by
ϵ and called electromotive force.
6. You can work this out using Kirchoff's loop rule(Kirchoff's second law). Imagine the air having infinite resistance. Then you can draw a loop going through the battery, along the wire and around in the air back to the other side of the wire. You then sum the voltage drops and emfs.
You can also use Kirchoff's loop rule in a circuit and derive the equation
ϵ=V+Ir, then let I tend to 0.