Interpreting a time series trend

I'm trying to identify a trend in some monthly precipitation time series data (2000-2020). The data are non-normal so I'm running a Mann Kendall test and a Sen's slope test to find the significance and magnitude of the trend. I've found that the data show a significant positive trend (tau = 0.4, p < 0.0001) but the Sen's slope analysis gives a magnitude of 0.0000456/month (p <0.0001). I'm slightly confused about how to interpret this because there's obviously a significant trend based on the p-values but this is so small that practically it seems almost non-significant? Any advice on how to interpret this would be great!