Below is a simple explanation of what real yields. This matters because if you run a long-term correlation analysis of real yields, i.e. TIPS yield, it's a near perfect inverse correlation to Gold save for temporary breakdowns.
Real Interest Rates = Nominal Yields - Inflation (CPI)
5-Year TIPS Yield = 5-Year U.S. Treasury Yield - Inflation (CPI)
5-Y TIPS Yield = 5Y Real Interest Rate
As bond yields fall while the CPI remains the same, ~2%, real interest rates fall. TIPS, or Treasury Inflation Protected Securities, rise in price as their yield, or real interest rates, fall. The correlation between TIPS and Gold is close to perfect on an inverse basis.