What does it mean by 'your pretty outside and inside'?

It simply means he likes your look on the outside and how you act like your attitude .

To add to your other question, that doesn't always means he likes you. You now know that he finds you pretty and that you have a good heart, but sometimes things just don't click. You may see a good looking guy who is helping out at a nursing home, but that doesn't mean your instantly in love with him. Go with your heart, and see if you could maybe like him back if that was not the case. Good Luck!:)