You can specify some or all fields when selecting. With the asterisk sign (* sign) you indicate that all fields must be used.
If you want to know all grape varieties that are present in the database you can make the following query:

select *
from grape_variety

With this query you select all data from the table "grape_variety". This query can be used in a program to fill in a list box and display it in a "dropdown listbox".
You can also specify the names of the fields (columns) as shown below. With the part "limit 10" you indicate that you want to see the first 10 records (of the 650).

select cust_id, surname, firstname
from customer
limit 10