 in BTC received at this address.

Examples:

The amount from transactions with at least 1 confirmation
> bitcoin-cli getreceivedbyaddress "bc1q09vm5lfy0j5reeulh4x5752q25uqqvz34hufdl"

The amount including unconfirmed transactions, zero confirmations
> bitcoin-cli getreceivedbyaddress "bc1q09vm5lfy0j5reeulh4x5752q25uqqvz34hufdl" 0

The amount with at least 6 confirmations
> bitcoin-cli getreceivedbyaddress "bc1q09vm5lfy0j5reeulh4x5752q25uqqvz34hufdl" 6

As a JSON-RPC call
> curl --user myusername --data-bin