In this circuit, a 5V voltage source is connected in parallel with a 6Ω resistor. Since they are in parallel, the voltage across the resistor is identical to the battery voltage (5V).
Calculations
Voltage (V): 5V
Resistance (R): 6Ω
Current (I): By Ohm's Law (I = V / R), I = 5V / 6Ω = 0.833 A