LAN means that only people who are on your network can join. If you want to open it to "the world" so to speak, you'll have to enable port forwarding in your router for port 25565/TCP and potentially add a firewall exception on the computer hosting the server.

I did this myself so if you have any questions just DM me.

@kelvinhall05 yeah i spent like a week trying to figure this out in college before realizing they had port forwarding locked down