Snowbirds are people who live in colder climates and travel to warmer locations during the winter months. Think about it like this: When it gets really cold outside, some people don't like it and want to go somewhere warmer. Just like how you might want to put on a warm sweater when it's chilly outside, snowbirds want to escape to a warmer place.
These people usually travel from the northern United States or Canada to destinations in the southern United States or other parts of the world where the climate is milder. They do this because they want to enjoy the sunshine, go swimming, and participate in outdoor activities during the winter when it's too cold where they live.
Snowbirds are usually retirees who are no longer working and have the time and resources for extended travel. They often rent or own second homes in their destination spots and stay there for several months at a time. This way they can escape the cold weather and enjoy a different lifestyle for part of the year.
In summary: Snowbirds are people who travel to warmer locations during the winter months because they don't like the cold weather. They usually are retired and take advantage of their free time and resources to travel to sunny destinations.