RGB data limits in imshow()

Question

I am trying to explore hyperspectral images and how to open, read and show them. For that I am using Spectral Python (SPy). When I call imshow() I get RGB data limits. What do these limits represent and how are they related to the intensities in the image itself?

from spectral import * 
import spectral.io.envi as envi
import numpy as np
import matplotlib.pyplot as plt
img = envi.open('Image_55.hdr', 'Image_55.raw')

imshow(img)

Output:

#ImageView object:
     Display bands       :  [0, 75, 149
     Interpolation       :  <default>
     RGB data limits     :
      R: [-0.04939008131623268, 9.653810501098633]
      G: [0.13590863347053528, 2.738651752471924]
      B: [0.23016303777694702, 5.807364463806152]