Pronunciation is the way a word or a language is spoken, or the manner in which someone utters a word. If one is said to have “correct pronunciation“, then it refers to both within a particular dialect.
Like many languages, English has wide variation in pronunciation, both historically and from dialect to dialect. In general, however, the regional dialects of English share a largely similar (though not identical) phonological system.
These interative charts of English pronunciation will help you to familiarize with how English sounds.