The Hash Ribbon is a market indicator that assumes that Bitcoin tends to reach a bottom when miners capitulate, i.e. when Bitcoin becomes too expensive to mine relative to the cost of mining. The Hash Ribbon indicates that the worst of the miner capitulation is over when the 30d MA of the hash rate crosses above the 60d MA (switch from light red to dark red areas). Times when this occurs and the price momentum switches from negative to positive have shown to be good buying opportunities (switch from dark red to white). The Hash Ribbon was created by Charles Edwards. For more information read his introductory article.
The Puell Multiple is calculated by dividing the daily issuance value of bitcoins (in USD) by the 365-day moving average of daily issuance value. This metric was created by David Puell. For a detailed description see this article by @cryptopoiesis.
90D Coin Days Destroyed is the 90 day rolling sum of Coin Days Destroyed (CDD) and shows the amount of coin days that have been destroyed over the past year. This version is age-adjusted meaning that we normalize by time in order to account for the increasing baseline as time goes by.
Reserve Risk is defined as price / HODL Bank. It is used to assess the confidence of long-term holders relative to the price of the native coin at any given point in time. When confidence is high and price is low, there is an attractive risk/reward to invest (Reserve Risk is low). When confidence is low and price is high then risk/reward is unattractive at that time (Reserve Risk is high).