When a battery is connected as shown, the negative terminal pushes negative electrons towards the junction.
The positive terminal pushes holes towards the junction.
If the voltage is high enough then the barrier will be overcome and current will flow through the junction.

There is a voltage across the diode. 0.6 for silicon, o.3 for germanium.

The junction is said to be FORWARD BIASED.

The P type is the anode of the diode, the N type the cathode, as shown by the diode symbol.

The resistor limits the current to a safe level.