On a hot humid summer day, you notice enormous, billowy clouds with broad flat bases. what can you predict about the weather? Explain

You can predict the weather will be hot, humid, and partly cloudy.

Such clouds may develop into thunderheads, though that development is not guaranteed. It is possible there will be thunderstorms, hail, and tornados developing in such conditions. The presence of an air mass of different (cooler) temperature will facilitate the development of extreme weather.