You can use either: - It has worlds of meaning. - It has a world of meaning. They both mean the same thing. The expressions "worlds of" or "a world of" are magnifiers. They are used to say something very strongly. In this example, It has a world of meaning. = It has worlds of meaning. = It means A LOT. = It is very important. = It has a very important meaning. Here are two other common ways of using the same magnifier: - It makes a world of a difference. = It makes a big difference. - Sushi in Japan and in Malaysia are worlds apart. = Sushi in Japan and in Malaysia are very different.