What does the number beside Pixel Dimensions in Resize panel referred to ???

Calculation:

Knowing that one kilobyte is 1024 bytes

https://dictionary.cambridge.org/fr/dictionnaire/anglais/kilobyte

And you need 3 RGB components values (red, green, blue)

(4114/1024) x (4114/1024) x 3 = 48,4228019714

If you are in 16 bits instead of 8, it's twice the size, same if you have two normal layers (not adjustement layers).

Actually i believe that's the estimated size of an uncompressed flattened Tiff and/or PSD (adobe isn't clear)

file in megabytes. It can also show in K(kilobytes) or G (gigabytes)

That is, if you were to save the file as a flattened Tiff and/or PSD with no compression, the file size shown in

Finder or Explorer would be about the same.

You can also see the same Document Sizes (Doc) in the left hand bottom corner of the document window and

here's what adobe says about that: