What is section
@GochikondaVijayaL - sections are the building blocks of your user interface. Check out this article for more details.
Section is a rule which will be used in Pega.How the UI looks like. You have many layouts in sections. Dynamic layout, Repeating dynamic layout and Embeeded section.
In dynamic layout we have option to select the layout as stacked, Inline grid double and Inline grid triple.
If you want all the fields that are in single line .You have to select the option as Inline.