Is "media" a collective noun? How can we use it in a sentence? Do we use "is" or "are"? What do we really mean by the word media?
It is plural, so make sure you use it that way, and it generally refers to the entire journalism profession.
The word "media" is the plural of "medium." "Media" as a collective noun means a few different things, including "multiple means of expression" (a mixed media painting, for example) or "the collective institution of news gathering organizations" ("I'll alert the media"). An individual journalist is considered a representative of the entire profession of news gathering, and can be referred to in shorthand as "media."
The singular form, "medium," has a slightly different connotation. It never refers to a single news-gathering organization. It refers instead to a specific means of expression or communication. All of television is a single medium. All of film making is a single medium, all painting is a medium, and so on. Any two of these can be called media.