MWR (money-weighted return) which is also called IRR (internal rate of return) is a compound growth rate. That's it.

If your MWR is 15%, then that means your money is growing at 15% per year. And that is likely to be the most important information you need. 

For each individual Investment, you can see its MWR (which is derived from the information you have provided). And on your Home page, you can see it for your entire portfolio of Investments.