Meaning of the colored bars

[Zalabard]

I don't find it as already answered: what is the meaning of the colored bars in the stat window (yellow-red-green-blue line beside any skill)?

[miadon]

yellow bar means how much you need to be taught in a skill.
blue means how much you can be taught with your current Progression Points
red means how much practical knowledge you will need.
green is how much you have completed.

[Zalabard]

Thanks so much