The function std::remove_if is part of the C++ Standard Library and is used to remove elements from a container that meet a specific condition. It takes three parameters: the beginning and end of the range to process, and a predicate function that defines the condition. Instead of actually removing elements, it shifts the remaining elements to the front and returns an iterator pointing to the new end of the range. To effectively remove the unwanted elements from the container, you typically follow std::remove_if with a call to the container's erase method. This combination allows you to clean up the container by removing the elements that were marked for removal, ensuring that the container only contains the desired elements.