When rotors are scored or pulsing, you have two options: resurface (machine) them or replace them. Resurfacing sounds cheaper, but on modern cars the math often favors just buying new rotors. Here is the cost trade-off.
What resurfacing does
Resurfacing (turning) machines a thin layer off both rotor faces to make them flat and smooth again, curing minor scoring and thickness variation that causes a pulse - see what is brake judder. It only works if the rotor has enough material to stay above its minimum thickness after cutting - see rotor minimum thickness and how to measure it.
Why it is often not worth it now
Modern rotors are made thinner and cheaper than they used to be. Many are too thin to safely machine, and the labor to turn a pair can approach or exceed the price of new rotors. That is why many shops no longer resurface and simply install new - it is often cheaper and gives a fresh, full-thickness rotor - see resurface vs replace rotors.
When resurfacing makes sense
Resurfacing can be worth it on thicker rotors that have plenty of material, on premium or hard-to-source rotors, or heavy-duty truck rotors where new ones are expensive. If the rotor is in-spec and only lightly scored, machining can save money.
The practical answer
Measure the rotor first. If it is too thin to machine, or new rotors cost about the same as turning, replace them - see when to replace rotors. Fit new rotors as a pair with quality pads and fresh hardware for the best value and result.