A well-read person has read a great many books, over years, across different subjects — and it shows when they talk. This is the key point: the word is not really about the reading. It is about what the reading left behind. Someone who has finished two hundred novels but never thinks about them is not what we mean. A well-read person can bring up a poet, a bit of history, an argument from a book they read a decade ago, and connect it to what you are saying now.

It is a compliment, and a fairly high one. It carries a hint of the old-fashioned scholar, someone whose learning came from books rather than from a degree or a job. So you can be well-read without a university education, and you can hold a doctorate without being well-read, if all you ever read was your own narrow field. Breadth is the whole idea.

You will hear it about people: he's very well-read, she's the best-read person I know. It fits a job reference, a book review, a description of a character, ordinary conversation about a friend. There is no unkindness in it — though someone showing off their reading is not praised as well-read; that person gets called pretentious.

Watch the pronunciation, because the spelling lies to you. The second part is said like the colour red (/red/), not like the word 'reed'. It is the past participle, the same 'read' as in 'I have read it'.