“Once upon a time, there was a kingdom ruled by a kind and beautiful queen.”

You're reading a children's book to your child. It's a fairy tale. You read the first line of the book, which says:

Once upon a time, there was a kingdom ruled by a kind and beautiful queen.

Once upon a time

This is a set phrase that children's fairy tales and story books start with. It means "one time" and suggests that the story happened a long time ago.

(someone) ruled a kingdom

Someone with complete power over a place "rules" it. This is usually a king, queen, emperor, etc. 

In modern days, you don't say that a president or prime minister "rules" the country that they're leaders of. That's because presidents and prime ministers don't have complete control; they have to follow certain rules and laws, and the citizens of the country can have them replaced.

Because of this, you should remember these phrases:

ruled the kingdom

ruled the empire

ruled the land

governs the nation

leads the country

a kind (person)

The word "kind" means "nice" and "not cruel". However, you don't hear it used much in daily conversation. People do use "kind" in some set expressions, like:

How kind of you.

And it's OK to tell someone to "be kind to ___":

Be kind to animals.

However, it sounds a little strange to describe someone as being "kind" in everyday speech. There are a few reasons for that:

1. "Kind" is a slightly formal word. It's used mostly in novels, children's books, and so on.
2. You usually describe someone as "kind" when they have more power or a higher social position. So, for example, a queen can be "kind" to her subjects, and a man can be "kind" to his pet. In earlier times, before there was equality between men and women, you could talk about a husband being "kind" to his wife.