for _ in range(n): a.append([c for c in input()])

This code snippet creates a 2D list called "a" which contains n sublists, where each sublist contains characters inputted by the user.

The "for _ in range(n)" loop is used to iterate n times and append a new sublist to "a" each time.

The "input()" function is used to prompt the user to enter a string of characters. The "for c in input()" loop is used to iterate through each character in the input string and append it to the current sublist being created.

For example, if n = 3 and the user enters the following three strings: "abc", "def", and "ghi", then the resulting "a" list would be:

[['a', 'b', 'c'], ['d', 'e', 'f'], ['g', 'h', 'i']]