HR stands for Hazard Ratio. 0.5 would mean something is half as likely as for the control group, while 2 would mean twice as likely. 0.37-0.89 is the confidenc

HR stands for Hazard Ratio. 0.5 would mean something is half as likely as for the control group, while 2 would mean twice as likely. 0.37-0.89 is the confidence interval at 95% confidence. So it's expected that if the study were repeated many times, the HR would appear to be within that (rather wide) range 95% of the time. This time it's 0.58. The main thing is that the upper bound 0.89 is quite a bit less than 1, so you could pretty confidently say there's a reduced risk, even if the amount is uncertain.