What do the numbers in the descriptor matrix represent?

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I am using the xfeatures::SURF detectAndCompute() function to pull out descriptors from an image.

I see that the descriptors are stored in a Mat object. (Mat descriptors). On visually displaying the Mat I get a very strange image.

And on displaying the Mat to the console output, I get a sequence of extremely seemingly random floating point numbers. Can anyone explain to me what these actually represent? I am trying to improve my understanding of descriptors.

Thank you.