Sharpe ratio measures how much risk your trading system takes to get the rewards. Exact calculation is complicated. Higher the sharp ratio the better it is. Sharpe ratio of above 1 is considered good, above 2 is very good, above 3 is excellent. Sharpe ratio is negative when trading system gives negative returns.
Note that higher Sharpe ratio doesn’t mean the maximum profits but it means a less volatile trading system , and the magnitude of drawdowns will be lesser in this system.
Sharpe ration of 0 means some incorrect calculation.