Okay, so imagine all the dogs in a big dog park. Some dogs are really big and strong, while others are smaller but still pretty tough. Now imagine that some of these dogs really like the color blue and they all hang out together. This group of blue-loving dogs is called the Blue Dog Coalition.
But wait, what does this have to do with grown-up stuff? Well, in the world of politics (which is when people make big decisions that affect everyone), there are groups of people called political parties. These are groups of people who share similar ideas about how to run the country.
The Blue Dog Coalition is a group of politicians who are part of the Democratic Party, one of the two major political parties in the United States. They are called "Blue Dogs" because they like to act more conservatively (careful with money) than some other Democrats. They also like to find common ground with Republicans (the other major political party).
Think of it like a group of dogs that doesn't always play with the other dogs in the park but instead hangs out with a smaller group of dogs that have similar beliefs. Just like how these dogs might look for new friends to play with and make compromises, the Blue Dog Coalition politicians try to work with other people in government to find solutions to big problems.