How sound is the hadith about the distance between the Earth and the nearest heaven being a 500-year journey, and where can it be found? And is what is meant by "journey" a human's journey?

The mention of the distance between the heaven and the earth, and the distance between the heavens being five hundred years, is correct, because it has supporting evidence and corroborations that validate it. The intent is that this distance takes five hundred years to traverse on foot. Knowing what this distance is measured by does not entail any practical action.