This feature allows you to manually add key-value data to each execution from a Code or Execution Data node, and then filter executions using those values.
in a Code node $execution.customData.set("ID", "123");
You can also override the entire object: $execution.customData.setAll({ key1: "value1", key2: "value2" });
Keys and values must be strings. A maximum of 10 key-value pairs is allowed, with each key up to 50 characters and each value up to 255 characters.