How to use data from a callback function in another function

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So going line by line here to help show you the flow of the issue:

ros::init(argc, argv, "pose");
ros::NodeHandle n;
ros::Subscriber sub = n.subscribe("/turtle1/pose", 1000, callback);

All good, initializing ROS, getting a nodehandle, creating a subscriber object and giving it the callback function to call. The spinner would then throw new messages received on that topic of that type to the function.

move() {while (ros::ok()) {...}}

Well, this is going to block infinitely. And while you're going to exit when ROS shuts down, no where in this infinite loop do you actually call a spin or spinOnce for the ROS messages building up to be processed (with a 1000 message queue size).

ros::spin();

Then you spin. This spin will only be called once your move() method exits (ie you end the program) so you're only just then starting to process messages.

What you could do instead is call ros::spinOnce() in your move() function and remove the ros::spin() from the end of your main function. That way you're processing messages in the callback and printing some values to screen.