Similar to the spatial dimension, the time-dimension must be discretized for the computer to work with it.
Unlike many other nodes, this node does not change its output based on its input nodes, but purely based on internal mechanics. These mechanics are very simple: if the start-button is pressed, the node will update its output with a speed given by the refresh-rate input. Each time a step is taken, it will add the dt-input to the current value of t. If t hits the T-input, the update automatically stops. Otherwise, the update can be stopped by pressing the stop-button, which shows up when the start-button is pressed. The reset button sets t=0.0 and stops the update. Changing the inputs into the node does not trigger a reset or something, the update will simply continue with the new information.