Understanding a formula

=ROUND(SUMIFS(INDEX($F$13:$N$150, ,MATCH(P2, $F$12:$N$12,0)), $C$14:$C$150, P2)/15,0)*11.35

I have received some wonderful help on the forum. I have not ever taken a class to understand formulas but I have tried my hand to create some to do what I need. I am
having some difficulty on a spread sheet with #Value filling in box after box and another is populating ######. I feel to understand how to get rid of these I need to understand what this formula is actually telling me so my question:

Can you tell me in words what the above formula is saying? ex.. this cells will round and sum if (????what does index stand for(how does the $F affect the sheet, does that mean the whole sheet etc. ) maybe a complicated question, I don't know. If some one can help that would be great. I will continue to study it out.

Thank you
mbauman

Reposting was in error. I did receive great explanations. Thank you.