This is more of a networking question than a node question. You'll have to be able to configure your gateway router / firewall to make it work. In addition, your ISP must permit inbound connections on the ports your listening to. Fortunately, this likely isn't going to be an issue, but just something to be aware of.

First, you'll need to configure your router to do port forwarding. Port forwarding will translate connections to a specific port on your router and then forward that request to the same port on a specific internal IP address on your local network. If your router has a firewall, you may also have to create a rule to let traffic on that port through. Most home routers won't need to do this.

Once your gateway router is set up, you'll need to find out the external IP address of your router. To find the external IP address you can go to a website such as https://whatismyipaddress.com/. Give this IP address along with the port to whoever you want to connect to your server.

Most ISPs assign IP addresses dynamically, so you'll have to check to see if your IP address has changed from time to time.

Once this is all set up and ports are forwarded to your local dev machine, you can launch your Node server and start seeing requests.

Be aware there are some risks with exposing your machine to the internet. Just be sure that you don't trust input to your server and maybe turn off port forwarding when you don't need it.

If you're not able to do any router configuration, look into ngrok. This will get though almost any NAT router or firewall. Be aware that the free version is limited to 40 connections per minute.