SELECT gets data from rows in a table
The SELECT keyword lets you get data from rows inside a table in your database, for example SELECT * FROM "mytablename"; gets all the columns (*) of all the rows in your table called mytablename.
You can select only specific columns from your table like SELECT "title", "author" FROM "longlist"; - get the title and author columns for all rows in the table called longlist (using the Booker Prize sample data).
Use SELECT DISTINCT to get rid of duplicate values for a column.