"My shoe is green."
Translation:La mia scarpa è verde.
Adjectives ending in e don't generally change according to gender and they also always take an I in the plural making it look masculine. But Italian also has quite a few color words that come from the name of nouns. These don't change either for gender or number. Many of those end in a, making the noun look feminine. This includes rosa, viola and ocra.
I most languages there are certain words that do not change from singular to plural. They are called "invariable". This is just one of them.
It's more common in those that end in "e" in the singular, but that's not a set rule. For instance, as stated below, rosa is also invariable.
Verde was actually one of the first Italian words I learned (beside food items), although I was learning French in school. We were on a car trip and some classical music came on the radio that I liked, so I asked who wrote it. My father replied Joe Green. I told him that classical composers never had names like that, so what was his real name. He responded, you may know him as Giuseppe Verde.