Surface issue

[jmoura_1]

Hello guys, i really apreciate if someone could help me.
Can anyone describe the meaning of these green lines indicated by the red arrows?
i only know the meaning of them when i want to pick some boundary.
what should i do in order to fix that surface in order to be able to some thickness? (i received an error message when i tried with this surface, i will put the image below)



Thank you!

 

[MrCATIA]

The green is highlighting gaps (or overlaps) between your surfaces. (zoom-in to see)

There are several solutions to this:
1. you could increase the Merging Distance in the Join
2. If the gaps are big, you could add some FILL surfaces to eliminate the gaps.
3. You could replace a surface with a new surface that extends to the adjacent surface.