The boy was playing with his toy car in the park.

Meaning: This means that the boy was in the middle of playing with his toy car in the park. He was probably having a lot of fun running around and pretending to drive the car. It's a fun thing to do on a nice day!

Choice of Words: The is an article that refers to a specific noun. Boy is a noun that refers to a young male child. Was playing is a verb phrase that means to engage in an activity for enjoyment. With is a preposition that shows a relationship between two things. His is a possessive pronoun that shows that the toy car belongs to the boy. Toy is a noun that refers to an object that is played with. Car is a noun that refers to a vehicle with wheels that is used for transportation. In is a preposition that shows a relationship between two things. The is an article that refers to a specific noun. Park is a noun that refers to a public area with trees and grass where people can relax and play. When you put all these words together, you get a sentence that tells a story about a boy playing with his toy car in the park.