Words that denote action are called action words or verbs.

Examples:

An old man lives in the forest.

What does the old man do?

A dwarf helps the old man.

What does the dwarf do?

The old man cuts wood for a living.

What does the old man do for a living?

The words lives, helps, and cuts denote action. They tell what one does. They are called action words or verbs.

Here are some more examples:

clean the yard

throw the garbage

write a letter