I have a raspberry pi I bought as a learning experience, my project is simple, maybe not so much for someone who doesn't know much.
I had a website hosted on apache2, I wanted to switch to nginx and so I did, or tried to.

Long story short, the service doesn't seem to start, I fed a "systemctl status nginx.service" to my terminal and it gave me this:

● nginx.service - A high performance web server and a reverse proxy server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Fri 2021-11-19 10:03:53 CET; 1min 22s ago
Docs: man:nginx(8)
Process: 1080 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=1/FAILURE)

Nov 19 10:03:53 raspberrypi systemd[1]: Starting A high performance web server and a reverse proxy server...
Nov 19 10:03:53 raspberrypi nginx[1080]: nginx: [emerg] a duplicate default server for 0.0.0.0:80 in /etc/nginx/sites-enabled/default:22
Nov 19 10:03:53 raspberrypi nginx[1080]: nginx: configuration file /etc/nginx/nginx.conf test failed
Nov 19 10:03:53 raspberrypi systemd[1]: nginx.service: Control process exited, code=exited, status=1/FAILURE
Nov 19 10:03:53 raspberrypi systemd[1]: nginx.service: Failed with result 'exit-code'.
Nov 19 10:03:53 raspberrypi systemd[1]: Failed to start A high performance web server and a reverse proxy server.