Note: You shouldn't be RETURNing anything for RP 16 Q3
Read the problem description carefully. It says that the program should print the output to the console/shell, and says nothing about returning a value.
So, you should really ask -- how do I make it PRINT the whole square as output? And Thu Ho provides some hints there that could be useful. Also, remember about string repetition (multiplication), which can help you avoid writing as many FOR loops. e.g. something like this:
print(' ' * 10)
print('*' * 20)