A more thorough explanation:

Definition: Rolling stock refers to movable property that is owned by a railroad, such as locomotives and rail cars.

Examples:

• A freight train consisting of multiple rail cars carrying goods across the country.
• A passenger train with several coaches and a locomotive pulling it along the tracks.

These examples illustrate rolling stock because they are both movable property that is owned by a railroad. The freight train is made up of multiple rail cars that are used to transport goods, while the passenger train has coaches for people to sit in and a locomotive to pull it along the tracks.