transform.position

transform.position is a value to read rather than a call: it is written without parentheses.

The API says: {x,y,z} proxies (R/W)

transform.position

function update(dt) {  const position = transform.position;}

transform.position is called with values of the shape its signature asks for. The code sits in update(dt), which the engine calls every frame: dt is the time since the last one, in seconds.