Maro most likely from a shortened Maroon which is a kind of brown!
Also resembles Marrom in Portuguese, which means Brown
And 'marron' in French which is one of the 2 ways of saying brown (I think it's for French in France and the other way 'brun' is for French in Québec), and it also resembles 'marrón' in Spanish which also means brown
I saw in this lessons also brun - just synonim, right? (compared to maro)