Hmm, it´s a bit of a tricky question. Because not everyone agrees when it comes to colours, the automakers name colour in a whim, then the industry of fridgies, then the guys that are into painting colours...
Anyway, I guess you could name your colour as some of shades of white of the following, could well be white ice (for "branco gelo"), but there is a wide wide range of whites in the colour pallete.
But then, brighty white? Off-white? We can´t possibly know what shade of white you wish.https://www.benjaminmoore.com/en-us/col ... r-families
As for "areia" it´s another hard problem to crack without context, it could be several kinds of it. Areia do deserto? (desert sand), areia praia? (beach sand).
Use control+F and see how many "sands" in the following scheme of colours...https://en.wikipedia.org/wiki/List_of_colors_(compact
Of course, you could use a workaround to bypass that by saying "the sofa and the rug, along with the center table match the sand colour
(scheme) of the curtains." (so, a generic way of referring to "areia" shade withouth specifically saying which one.)
Curtains these days, can be of a dark (and hot colour), perhaps your sand could be even "brick red" or even "maroon" curtains? well, my guesswork! Just guesswork...