Hello,
What is the importance of extinction coefficient? And molar extinction coefficient? If the value is too large like 100000,what information we get from it?

The extinction coefficient describes how well a substance scatters and absorbs EM radiation. It's a function of the material and the wavelength of the EM.

Something like glass would have a very low extinction coefficient for visible light as it is hardly absorbed or scattered even through very thick panes of glass, whereas something like wood would have a very high coefficient, since almost all light is scattered and absorbed within a very small distance.