Assuming you are referring to this: "N5 provides around 15% higher performance at the iso-power or, alternatively, up to 30% power reduction at iso-performance.

Assuming you are referring to this: "N5 provides around 15% higher performance at the iso-power or, alternatively, up to 30% power reduction at iso-performance." They are just saying that for the same power usage as previous tech, they get 15% more performance, or 30% power reduction while achieving same performance as previously acheivable."