How does the video celebrate reaching a goal?

The video celebrates reaching a goal with enthusiastic verbal acknowledgment and visual effects. As stated in the transcript, the moment of achievement is marked with an excited 'Yay' exclamation, creating an atmosphere of joy and accomplishment. Most notably, the celebration includes confetti, which provides a visually engaging way to mark the milestone. This combination of verbal and visual celebration techniques enhances the experience of achievement, making the accomplishment more memorable and rewarding for those involved.