ball.sort(key=lambda x:x[0])

This is a Python code snippet that sorts a list of tuples called "ball" based on the first element of each tuple.

The "key" parameter is used to specify a function that will be applied to each element in the list before sorting. In this case, the lambda function is used to extract the first element of each tuple and use it as the sorting key.

After the sorting is complete, the original list "ball" will be modified and the tuples will be ordered based on the first element in ascending order.