"Literally" formally means exactly, but informally it can be used as a form of emphasis or to mean "figuratively".
Many people think that the informal use is a recent development, and perhaps a sign that the speaker has a poor grasp of English.
They are incorrect on both counts. Examples of older use by people who undoubtedly had excellent grasps of English are found in the writings of F. Scott Fitzgerald, James Joyce, Charlotte Bronte, Charles Dickens, and others going at least as far back as 1769. More on this in this article from Merriam-Webster on the angry comments directed at them by readers who think MW is corrupting the language [1].
They note that most other major dictionaries agree (in a middle finger to the critics, they say "Literally ever modern dictionary includes this definition"). They also note it has been in MW since 1909...I think they are trying to imply that the people who just noticed it there and were writing those angry comments are slow.
Sadly, this means people like you and me, who would prefer it to just have the formal meaning should really give up correcting or making fun of the informal usage, lest we literally look like idiots.
[1] https://www.merriam-webster.com/words-at-play/misuse-of-lite...