We Daltonians can see color, we are just unable to distinguish between certain colors. For example, red, green, orange, and brown are indistinquishable as are blue and purple. But yellow is not a problem for me. That's why I can pay parchisi as long as I get to be yellow. Black and Navy blue sometimes appear to be the same color too, especially in a dark background.
But I have no problem playing chess, checkers, backgammon.
My family loves a game called Rook which has the suits, but no symbols. The colors are black, red, green and yellow. Since red and green were the indistinguishable to me, my mom wrote R or G on the cards and wrote Parker Brothers and asked them to switch green to blue. They didnt, but now all suits have their color spelled out.
She also wrote the makers of Uno suggesting they swap gray for green, but they did not alter the deck to make it payable for us Daltonians until last month (September 2017).
No, there is no difference in Esperanto between "We see colour" and "We see a colour". Both would be, "Ni vidas koloron". The -n at the end of "koloron" is because the word is in the accusative case - we see (a) colour, the colour doesn't see us. Esperanto doesn't have an indefinite article (like the English a and an.
Because plurals in Esperanto take a -j ending, so "We see colours" would be "Ni vidas kolorojn", but we were given "Ni vidas koloron, "which is singular, so means one colour.