Python lists can contain different types of elements. They can have integers, strings, floating-point numbers etc. They can also contain other lists:
l = [4, 5, 'hi', 3.14, ['how', 'are', 'you', '?'], 64]
print(l) # hi
print(l) # h
inner = l
print(inner) # are
print(l) # are
This is an example of a list in python that contains another list in it. The operations with the nested list are exactly the same as the ones with the outer one. One can add elements with append, or remove them with pop, etc. Therefore the indexing would work like we are accessing a nested list from within a list.