The simulation shows a simple circuit, with a battery, a switch, a
resistor, and a few wires.
Conventional current shows the Ben Franklin view of the circuit, that
the flowing charges are positive (shown in red).
In actuality, the flowing charges in the circuit outside the battery are
negative (shown in blue) - they are electrons - while the ones inside
the battery are positive. For the "Actual" situation, note what happens
at the two terminals of the battery. This looks a bit like magic, but is
actually chemistry.