The search results show that there are multiple Walmart stores in Miami, Florida. To find the hours for a specific store, you can visit the Walmart website and search for the store using the store finder tool. Once you find the store, you can click on it to see its hours of operation. Alternatively, you can call the store directly to ask about their hours. One of the stores listed in the search results, store 5854, is open every day from 6 am. However, it is important to note that store hours may vary by location and day, so it is best to check with the specific store you plan to visit.