.insert

Question

words = ["Python", "fun"]
index = 1
words.insert(index, "is")
print(words)

ON LINE TWO AND THREE, THE VARIABLE INDEX = 1 SO LINE FOUR IS ACTUALLY words.insert(1, "is"), WHAT DOES THE 1 REALLY MEAN IF WE NOT INDEXING BECAUSE THAT "is" gets inserted between the two words

Answer 1

"is" gets inserted as the list's element number 1 (so the second element) and the remaining one(s) to the right get shifted by one. The only element is "fun", which gets located on the third position (list's element number 2).

Answer 2

on the first line. "python" is in 0 index and "fun" is in 1 index..
on the third line. it basically inserts the string "is" in index 1 and the others move by 1.

It enables you to insert something at the given index.