an icc will marry ink, printer and media colors
so when you want a blue, you will get a blue
example:
buy an epson heat transfer ink from supplier
download icc for jpss papers, download another icc for 3g opaque papers
all the work is done for you to marry the three components (and changes depending on media you choose, jpss or 3g)
even though your monitor shows pink, but you have chosen blue, it will print true blue
you could even have a physical pantone color guide and use that for your colors and the icc will print those colors
(i think, someone may correct me here)