I looked it up because I was having trouble distinguishing it as well.
"While most of the sounds are pretty straightforward, the "r" sounds deserve careful attention for English speakers because there is no equivalent sound in English. It is more similar to the "r" sound in Spanish.
What works for some English speakers (even if it may not be technically correct) is to shape the lips something like the sound that is made for the English "r," but to make the sound with a single trill or flap of the tongue against the front of the palate."
The consonant sound is called an alveolar tap (in the International Phonetic Alphabet it's spelled /ɾ/), and is the sound that American English speakers use when an alveolar plosive (T or D sound) falls between vowels, such as in "latter" and "ladder" (both pronounced /ˈlæ.ɾəɹ/ in American English.) The vowel sound is roughly like "oh" /oʊ/ but resisting the urge to close your mouth while still making sound.
In short, "ろ" is pronounced /ɾo/
If you read the introductions for the lesson sections it tells you it sounds like a soft "d". Every time I hear しろ Shiro, I hear shi-dough. I think it's because "r" and "d" sounds are made almost the same way when speaking (depending on the word, if it's soft or hard, and if you speak American English, too I guess).
Here's how I remember the colors.
like "ow" or "ouch",
like you just got a bruise.
Bruises sometimes look BLUE.
like blood is icky.
icky blood is RED.
I had trouble with white. None of my mnemonics stuck until I this. It's kind of terrible, but is something I keep reading in political commentaries.
President Trump is joked to have a Fake Orange Tan. They refer to him as Orange.
AND Cheetos are a cheesy snack (potato chip like snack in the US) whose coating/seasoning turns your fingers Orange.
shi-to (sounds like, in English)
Cheetos = Orange.
The WHITE man looks (Cheeto) Orange.
Ya it's based on a not nice rhetoric in popular culture, and current news here in the USA. Might not work elsewhere., or in the future, when the rhetoric stops. But you could still use something similar using Cheetos and the color white..
Hope you find a way to remember them too.
I listened to the woman's voice at the top of this thread, and she's clearly saying "shiro". I think it might sound more like a "d" to you because the Japanese "r" sound is made by placing your tongue at the roof of your mouth in a similar way to how we make the "d" sound in English.
Technically, its all colors, but it's LIGHT colors. There's a difference between pigment colors and light colors. For instance, if you colored a little space on a peice of paper with all of the colors in your 100 peice crayon box, you would get as close to black as you could. But if the primary light (as in sunlight) colors (red, green, blue) all came together, it would make white. Think that if a rainbow combined all of its colors, it would be white. I'm sorry for the scientific answer, I couldn't help it.
Colors have both a noun form and an adjective form.
The original Japanese colors specifically have an い-adjective form (White, blue, red, black)
青・あお・Blue (noun)・"Blue is a pretty color"
青い・あおい・Blue (adjective)・"Blue shoes"
赤・あか・Red (noun)・"My favorite color is red"
赤い・あかい・Red (adjective)・"Apples are red"
The い at the end allows it to directly modify another noun, as well as conjugate like a verb:
白くない is not white 白かった was white 白くなかった was not white