One million.
While power levels are only formalized for the Dragon Ball super series and not necessarily canonical for other parts of the franchise, 1 million is the latest calculable approximation to Goku’s power level given in Dragon Ball Super. For contextual purposes, a typical Saiyan like Vegeta would have between 20-31 times this number of power levels. The word “million” is an adjective used as a unit of measure when discussing someone’s power – it is not divisible or convertible as it would be with weights or lengths. There is no inherent limit on how high one can make a power level go, but there may well be empirical limits based on observed accomplishments within canon (which has seen comparatively few beings).