Positive and negative terminals on a battery
The convention for current flow was established before the electron was discovered (by J.J.Thomson in 1897). The convention is that current flows from + to -. We now know that, in fact, the mobile charges are electrons and flow from - to + but the convention has endured and we all use + to - flow but keep the reality in the back of our minds.

As is universal practice in maths, physics and general engineering, + is higher than - so we refer to the positive terminal of a battery or power supply as having higher potential. (Conventional) current will flow from the higher potential to the lower, i.e., from + to -.







simulate this circuit &ndash; Schematic created using CircuitLab

The magnitude of the current will, for a resistance load, be proportional to the voltage or potential difference between the terminals and inversely proportional to the resistance between the terminals. This is succinctly stated in Ohm's law.

$$ V = I \cdot R$$

which can be written as 

$$ I = \frac {V}{R}$$