The Sharpe Ratio is a ratio that puts the return achieved in relation to the risk incurred. To this end, the risk-free rate (which you would get with a risk-free investment such as a savings book) is subtracted from the achieved return, and this reduced income is divided by the investment’s volatility.
The result is the income per risk unit. The greater the value of the ratio, the more likely that the risk accepted will pay off. A negative value means that the risk-free rate was not surpassed and results in a limited comparability.