Relays are very simple. You have signal output on your board - you could add external relay for 2$ each. You only need to have the output so it triggers the relay with 5-24v, having in mind that the LPT breakout boards have limited number of inputs and outputs and the more industrial boards could have 50 digital inputs or outputs or even 100.
Some boards have integrated a couple of relays for the coolant, spindle and so, some dont have. As i said relays are very cheap.
Thats all you will ever need to know.