Where it helps is when you want to display say a JPEG that is tagged with color info. In that case, there will be a table which essentially says: here is how to convert RGB values (which have no INTRINSIC ie OBJECTIVE meaning) into specific frequencies and amplitudes of light (ie something that is objective).
The color management software takes that table, uses it in conjunction with a table associated with the display device (which likewise says how specific RGB values sent to it will translate into specific frequencies of light appearing on the device), and maps each pixel in the JPEG through these tables. The end result, when done properly, is that the JPEG will appear the same on all screens, and the way it looked when the image was captured. (Subject, of course, to HW limitations.)
Likewise when you now want to print your JPEG.