It is not possible. Parrots, even the most intelligent, must a learn a foreign language not even developed by the same race. Without any possible way to communicate with them in their own language, certain things wold not be explainable.
To make it comparable, imagine yourself as a five year-old trying to learn to talk with dogs. No one understands you, and you can only tell what the barks mean by the body language of the dogs themselves.
With African greys being the most intelligent of parrots, they have the most stunnig accomplishments. Some have learned over 5000 words and use them in the correct context.
I understand English perfectly well, as I am English.
Shakespearean language is English. "I will kill you" is perfectly straightforward English and means "I will kill you".
I understand perfectly well
An ESL job is a job in a English as a Second Language learning facility, where immigrants who understand minimal English can learn and understand the language.
because they can't understand it
English
I don't know what "other people" you're talking about. Perhaps they speak some other language instead and are wondering why you don't understand Klingon (or whatever). Or maybe they nominally speak English, and they're just really dumb. One must also consider the possibility that they understand English perfectly and you're just a poor communicator.
If you understand the language,you reply YES,if not,NO if you understand a little bit,you reply SOME.
Like many languages, English is a language that is fairly easy to speak very well. Perfectly? - I doubt that anybody speaks English perfectly! But seriously, languages are always evolving, so it is impossible to say what is 'perfect' at any given moment.
If they have learned the language then of course they can.
Yes, it is possible to lip-read in languages other than English. Lip-reading involves watching a person's lips, facial expressions, and body language to understand what they are saying. The ability to lip-read in a particular language depends on the individual's familiarity with that language's phonetic patterns and speech movements.
An ESL job is a job in a English as a Second Language learning facility, where immigrants who understand minimal English can learn and understand the language.