Manying,
What kind of object is it? For the most part, objects are containers that don't provide for text to flow in or out of them. The notable exception is the linked text box.
If that object is the only thing in your Pages document and if that document is a Page Layout template, you will have to add another object to continue developing the document. If you are not familiar with the difference between Page Layout and Word Processing templates in Pages, it would be a good idea to download the Pages User Guide from the Help menu and read the first few chapters.
Jerry