Help explaining a solution for Python Challenge

I was able to solve the python code challenge in the tuples section

"Create a function named combo() that takes two iterables and returns a list of tuples. Each tuple should hold the first item in each list, then the second set, then the third, and so on. Assume the iterables will be the same length."

my solution:

def combo(it1, it2):
  output = []
  for index, item in enumerate(it2):
    output.append ((it1[index], item))
  return output

Now I was mostly just trying different things to try to solve it... I would like an in depth explanation (line by line) as to what exactly is being processed and why using plain english (not too much code jargon as I am brand new to coding) as much as possible.

My interpretation is something like

def combo(it1, it2):  #define the combo function
  output = []  #place holder variable established
  for index, item in enumerate(it2): #for position, item in broken down iterable 2 do the following **This step is still fuzzy in my understanding because I am a little confused about how the index and item are interpreted 
    output.append ((it1[index], item))  #take placeholder and add on (append) the it1 position and item tuples given **this step is still a little confusing to me as well because of the index and item part in the append()
  return output #show result

My biggest confusion I guess is understanding the whole index definition (basically just a given position in something..?) and how exactly 'item' is used/interpreted in 'for' loops and even how to "read" how a 'for' loop is done. I like to kind of read through each line in plain english (interpret it) so that I understand step by step what exactly is being done.

It may seem odd to ask about this considering I managed to solve it, but I want to COMPLETELY understand as to why it worked so that in the future It is less trial and error and more step by step analysis of the problem and finding the solution, if that makes sense.

Thanks.