This is an indicator which shows your position's average price of you started dollar cost averaging 30, 60, 90, 120, 150 and 180 bars ago.
Dollar Cost Averaging (DCA) means buying into a position by investing a fixed sum every bar (for example every day or every week). This way, when the coin of stock goes down, you buy more of the stock.
Some exchanges such as Coinbase, Revolut or River Financial offer this option of entering a position using automatic DCA. It's a kind of "set it and forget it" investment (but you still have to be careful to sell your position into profit).
There are people who DCA into an ETF every week for many years, and so build a position at a very advantageous average price.