Red
noun
The kanji and the word are exactly the same. That means they share meanings as well.
あか
This has the same reading as the kanji you learned, meaning you know the reading!
ケチャップの赤はトマトの赤です。
Ketchup's red color comes from red tomatoes.
赤パプリカは、すきですか？
Do you like red peppers?
あのライトが赤になったら、車を止めて下さい。
Stop the car when that light turns red.