The Columns layout web part provides a CSS-based column layout for content. Each column defines a separate web part zone, so any type of content may be added into it.
For more information, see Working with layout web parts.
Left column
Left columns are DIVs floated to the left. There can be multiple left columns.
Right column
Right columns are DIVs floated to the right. There can be multiple right columns.
Column layout
This column layout web part provides a DIV (CSS based) layout for your page. Each column contains a web part zone.
The center column fills in the remaining space in the layout.
Even though this layout is DIV based, it supports equaling of the column heights to provide a table-like experience.