You are confusing the dynamic range that can be contained in a RAW file with the adjustment that tells Lightroom what portion of that dynamic range to place in the center of the displayed picture's dynamic range.
A photo can have some parts that are so bright they are pure white and other parts so dark they are pure black. The distance between the white parts and the black parts, expressed as Exposure Values (EV) are the image's dynamic range.
Your camera can detect differences in brightness of about 13 stops (the other EV in the camera's DR is eaten up by the noise floor - the level of brightness that is indistinguishable from digital noise). But the best an 8-bit image, such as a JPEG, can do is somewhere between 6 or 7 stops. This means a typical monitor that is 8-bits per color channel is also limited to about 6-7 stops. So are most printer ink and paper combinations.
When you open a RAW image in Lightroom, what you see on the screen is an 8-bit conversion of the RAW data using your LR default settings. As you move the controls, including the exposure slider, LR recomputes that 8-bit conversion and displays the results. Once you are happy with your edits, you can export the image and the conversion you see on the screen is saved as an 8-bit JPEG.
Some of the adjustments you can make in LR squeeze the wider 14-bit range between the brightest and darkest areas of the scene into the narrower range of an 8-bit image. With the exposure adjustment, though, you are telling LR to shift the point at which everything brighter than a particular brightness value is rendered as white and everything darker than a particular brightness value is rendered as black without changing the distance between the white and black points.
See also When comparing sensor dynamic range, what are those numbers based on?
And What does a dynamic range difference of 2.7 EV really represent?