In plain English
Sharpe is a report card: how much return you got per unit of bumpiness over the last year. High Sharpe means a smooth grind up. Low or negative Sharpe means a messy or losing year.
Here it is painted onto the price line as colored dots. Green-ish dots are capitulation-like low Sharpe (historically often a better place to look). Hot pink is a euphoric high-Sharpe stretch.