Although the Left/Right designation is used in the case of parallel runs to avoid confusion, it is also used with single runs to inform pilots of which side the circuit is on.
Thus, in a pre-flight briefing, a pilot might be told that his runway is '25L with EFATOs to the right.' This means that his runway is runway 25, at 250 degrees (as explained above), the circuit is an anticlockwise one, and if he has an engine failure, he is to head right. Any aircraft on a right-handed circuit will be known to be having problems and so can be given priority.