AI (Artificial intelligence) is a subfield of computer science, that was created in the 1960s. It was (is) concerned with solving tasks that are easy for humans, but hard for computers. The term comes from the massive computers of the 50s (prof McArthy).
Narrow AI or Weak AI is doing specific tasks better than humans. NLP, image recognition, predictions, translation, etc. Its confined to very narrow tasks. No meaning, just tasks. Its not “General AI” (see below), otherwise the machine would get tired of your orders. The symbolic systems approach is also Weak AI.
Strong AI would be a system that can do anything a human can (perhaps without purely physical things). This is fairly generic, and includes all kinds of tasks, such as planning, moving around in the world, recognizing objects and sounds, speaking, translating, feeling emotions, performing social or business transactions, creative work (making art or poetry), etc.
Despite what is said by the media, Narrow AI is what is around today in technology. And Strong AI or conscious machines are (and will) be science fiction for many years to come.