The most prominent error in the message is the improper grammar and phrasing. The message should be written as follows: "Hello Stacy, I hope all is well. I spoke with the manager, and she said that you need to wait for 48 hours before she responds to you. Will this work? John"

The most prominent error in the message is the incorrect grammar and syntax. The sentence structure and word choice are not appropriate for formal or professional communication. Additionally, "I speaks" should be "I spoke," and "48 hour" should be "48 hours" for proper grammatical correctness. Also, the phrase "Hope good is all" is not a conventional or grammatically correct way to express well wishes in English. Finally, the message lacks proper punctuation and capitalization. The message could be improved by revising it to: "Hello Stacy, I hope all is well. I spoke with the manager, and she mentioned that you need to wait 48 hours for her response. Does that work for you? John"