The resulting list of tables are 'data products' that contain the information that you searched for. Each table in the list has an ID number, a title, and the dataset from which the table was constructed (i.e., '2010 ACS 5-year estimate', or '2000 SF3 Sample Data'). If you are unsure about where the data came from, click on the info icon in the About column.
SF files are summary files from the decennial censuses.
Clicking on a table title will take you to the table. The rows of the table are a pre-defined set of topics that are contained in a given data product such that each table will contain your topic of interest and probably more information as well.
The columns represent the geographies, and will depend on what geographies you chose in your search.
If you are unsure of terminology or acronyms, you can use the Glossary for more information.
Wondering what exactly a census tract is? Find the answer here, on the Census Bureau website.