You are correct, C, M, Y and K stands for Cyan, Magenta, Yellow and Black. Those are percentages of CMYK colors which are measured from 0 to 100% while RGB values are represented with numbers 0 to 255. Numbers for RGB values are creating color inside circle or inside square in the middle in your screenshot and those numbers translated to CMYK colors are represented on the right side: C: 4%, M: 28%, Y: 28% and K: 0%.
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