As subjects and direct objects of a verb

• You can use a noun as the subject of a sentence to show the focus or topic of that sentence.
• The subject acts with a verb to show who or what is doing the action:

Jack (S) sells (V) houses.

• You can use a noun as the direct object of a transitive (action) verb.
• The direct object follows the verb to show who or what receives the action of the verb:

Bruce kicked (V) the ball (DO).