Imagine a slow trend line. One market month can move sharply and tell a misleading story. The 7-year moving average takes the last 84 months, averages them, then draws a calmer line.
What is it for?
It reduces noise. Instead of focusing only on the latest violent move, it helps read the broader direction.
Why moving?
Each month, the oldest month leaves the calculation and the newest month enters. The line therefore moves slowly with the market.
Why 7 years?
Because this is not meant to produce a fast buy/sell signal. The goal is to avoid changing your mind after every few-week shake.
On the gold / bonds chart, the blue line is not a prediction: it is a filter. If the ratio only moves briefly around that line, it does not say much. If it stays above for a long time, gold dominates bonds: the market may be looking more at inflation risk and weakening money. If it stays below for a long time, bonds regain control: the signal becomes more deflationary, or points to a colder world.