Output data can be given aliases

SELECT 'Elena' AS first_name

will output the text Elena with the header first_name

SELECT 'Elena' AS first_name, 18 AS age

will output the text Elena with the header first_name, and the number 18 with the header age.

The keyword AS can be omitted:

SELECT 'Elena' first_name, 18 age

will give the same result.

In aliases you can use not only Latin letters, but also spaces and Cyrillic. In this case the alias must be enclosed in double quotes:

SELECT
	'Elena' "Name",
	9*2 "Age",
	'red' || 'car' "color of auto"

By the way, in Microsoft SQL Server, square brackets are used for aliases instead of double quotes:

SELECT
	'Elena' [Name],
	9*2 [Age],
	'red' || 'car' [color of auto]

And in MySQL - backticks:

SELECT
	'Elena' `Name`,
	9*2 `Age`,
	'red' || 'car' `color of auto`