It means that you accept all cookies - in Europe/UK and California we get popups when we access a site for the first time and can choose to accept or decline nonessential cookies. On flyertalk there are quite a few cookies, and none of them are especially tasty. But as you're in China, all your web activity is tracked in many different ways already, VPN or not, so a few cookies from Flyertalk should be the least of your worries.