If you looked at demo pages of wordpress themes authors of theme generally use lorem ipsum or dummy text to show the functional part of the design.

Create Dummy Text Online at Blind Text Generator. You can also choose from 10 dummy texts like Lorem ipsum, Cicero, Li Europan lingues, Far far away, Werther, Kafka, Pangram and English Alphabets and Numeric’s.You can also set the number of Words / Characters and number of paragraphs and in the advanced options you can set CSS tags like Font, Font Style, Size, Height, Decoration etc.

Create Dummy Text @ Blind Text Generator.