Circulating supply, in the context of cryptocurrency pertains to the best approximation of the amount of coins that are being issued into the market for purchase by cryptocurrency holders.
The circulating supply of a cryptocurrency may increase or decrease through time. For instance, the circulating supply of Bitcoin may increase in increments until such a time that all 21 million coins are placed out in circulation. The increase is owed to the process of mining that is responsible for coming up with coins within an average of 10 minutes.
The decrease in the circulating supply may happen through what is called a “coin burn” events administered by Binance. Such removes coins from the market.