"Can literally mean figuratively?
One of the definitions of literally that we provide is "in effect, virtually—used in an exaggerated way to emphasize a statement or description that is not literally true or possible." Some find this objectionable on the grounds that it is not the primary meaning of the word, "with the meaning of each individual word given exactly." However, this extended definition of literally is commonly used and is not quite the same meaning as figuratively ("with a meaning that is metaphorical rather than literal").
Is the extended use of literally new?
The "in effect; virtually" meaning of literally is not a new sense. It has been in regular use since the 18th century and may be found in the writings of Mark Twain, Charlotte Brontë, James Joyce, and many others.
Is the extended use of literally slang?
Among the meanings of literally is one which many people find problematic: "in effect, virtually—used in an exaggerated way to emphasize a statement or description that is not literally true or possible." Neither this nor any of the other meanings of literally is what we would consider slang. This sense has been in standard use by many esteemed writers since the 18th century." (https://www.merriam-webster.com/dictionary/literally)