ok so you do a plain nmap scan, nmap ip address, and it gives you a long list of open ports with brief descriptions.

(then i tried doing the same thing plus -sV but it seemed to be taking an infinitely long time, maybe because the port list was so long? anyway though:)

how do you go about figuring out which port to use which exploit on? the guy in the video i watched (https://www.youtube.com/watch?v=K7y_-JtpZ7I) just seemed to know off the top of his head which port was which and what a good exploit to try would be.

how do i go about learning this? should i just do searches / ask ai and start learning thing by thing, or, is there like a database, a resource, a tool, anything normally used to assess these? nmap returns a huge list of ports, metasploit searches return a huge list of exploits. where do you start learning which ports and exploits should be tried, or, are there things you use to figure this out?