1"美丽" means" beautiful"
2another meaning of "千万" is an emphasis.for example,if you hv something must do or must not do ,and u want to emphasize your tone,so u can use "千万" in front of must do,like "你千万要记住这句话。..."“你千万不要出门。” It‘s just an emphasis
3We don’t use “妳”,we only use “你”