ACLs and Routes Maps are my biggest struggle in my network studies. I understand your first sentence about statement 10. Your second sentence about statement 20 is confusing.
“If you don’t add statement 20 then ALL traffic will be dropped. For example, when 192.168.1.1 tries to reach 192.168.1.2, it would be dropped. That’s why we added statement 20”
Why would that be the case? The Access-list and statement 10 are very specific in saying if any host tries to reach 192.168.1.100 (the server) – DROP IT. That being the case…. Why would 192.168.1.1 to be able to reach 192.168.1.2? I don’t see how all traffic is dropped when we are so specific with the creation of the ACL 192.168.1.100