Here's why:
* Proper nouns are specific names of people, places, or things. They are always capitalized. Examples include:
* People: John, Mary, Queen Elizabeth
* Places: London, Mount Everest, the Pacific Ocean
* Things: the Eiffel Tower, the Great Wall of China
* Soy beans is a common noun referring to a type of bean. Common nouns are general names and are not capitalized unless they are at the beginning of a sentence.
Let me know if you have any other questions!