Some people have thousands (literally!) of recipes in their Plan to Eat account. As they are adding recipes to their collection they use the queue as a temporary holding spot for new recipes that they want to try or easily add to their Planner. You can add recipes to your queue to meal plan in the near future, or as a place to save your favorite recipes.
When you plan a recipe we display a tag similar to "1 recently" on the recipe. Recently planned recipes are recipes that have been planned from 2 weeks ago, to 2 weeks from now. Periodically you can use the "Clear Recently Planned" button to remove any recently planned recipes from the queue.