I have 7 hours stopover at the HK airport. what should i do?

Upon landing, you can take airport express to get to HK Station first. It takes around 25 mins on the way.
Then walk to Central Area. As I know, there are many nice restaurants for you to choose. You can taste some delicious local foods. In addition, this area can be regarded as one of the most prosperous place to go shopping. You can find many famous brands there. Have fun! Just be aware of the time to go back.