What they're for
A mention of your business on another site, with the same name, address and phone number, is a small vote that the business is real and is where it says it is. Search engines line these up across the web.
It matters most for a business that's new or not widely known, which is most contractors under a few years old. Once your name is well established, another listing on another site adds almost nothing.
The short list, done once
Your Google Business Profile first, then the other big map and search platforms, then your state or trade license listing, your supplier's find-a-dealer page, your chamber of commerce, and the neighborhood app people in your towns use.
That's an afternoon of typing, and then it's done. Put the exact same name, address and phone number into every one, from a note you keep, so nothing drifts.
Where you have a choice, the local ones beat the national ones. A page on your county association's site is worth more than a profile on a directory nobody in your town has heard of.
What to refuse
A monthly service to keep your listings in sync. It's an afternoon of work sold as a subscription, and the sync usually means the service owns the listings, so canceling can revert them.
Submission blasts to hundreds of sites. Google's spam policy names low-quality directory links and automated link-building services directly, so you'd be paying for something Google wrote a rule against.
What it can't do
It can't put you on a town's list. Being in fifty directories doesn't put a page about your work in that town on your own website, and that page is the thing a town search is choosing between.
This is the mix-up worth being clear about, because it's what gets sold. Listings help machines agree that you exist. Pages are what get you found for the work.