"One says that Esperanto is an easy language."
Translation:Oni diras, ke Esperanto estas facila lingvo.
Esperanto estAS facilA kaj belA ✓
Esperanto facilAS KAJ belAS ✓
Esperanto estAS facilAS kaj belAS X
Since I can't say it in Esperanto clearly.... Unless followed by sentence breaks such as "kaj" and "ke", you can only use one of the following action ending per sentence: "-as" "-os" "-is" "-us" "-u"
If you already have one of the above and do not have a "sentence breaker", then the next action word(s) needs to end with "-i", which essentially is it's most basic form.
Also, if you use a describing-action word such as "esti" as the main action, you can change the following action words into their description forms by changing their endings to "-a".
Hope that helps!