What does "the faces a sea of red means?"?

Question

I read it on a book.

Answer 1

that all the faces were red, either because of the sun, embarrasment or racial perception?

Answer 2

I think it would be wise to give some more of the text to allow us to see the context of the line you're looking for - also is it a story, play, poem? Who wrote it and when - all of these will allow us answerers to give you a better answer than "dunno"

Once we know the a bit more about the source and the line's context, we can comment on possible meanings.