Conditional summing of rows - google-sheets

Question

I have a summary spreadsheet that I want to grab data off another larger spreadsheet. I have read a bunch of questions and tried dsum and if statements but still I cannot figure out how to do this.
The larger spreadsheet has multiple columns. I want the function to filter the rows (based on two different criteria in two different columns) and then sum one cell in each of the filtered rows. So kind of like an IF statement but IF falls down because it tests all the rows and comes back false.
So if I sort of adapted an 'IF' statement it would look like this:
=FUNCTION(LargeSpreadhseet!F:F="CharacterString" & LargeSpreadsheet!A:A="CharacterString",sum cell X in rows meeting these 2 criteria,"Otherwise Nil")
Example:
ColHead1 ColHead2 ColHead3 ColHead4
A 23 GREEN 34
B 34 BLUE 45
C 45 BLACK 56
A 56 GREEN 56
B 45 WHITE 45
If I want the function to sum 34 and 56 and return this value, based on the fact that ColHead1=A and ColHead3=GREEN, so summing the cells in ColHead4 of the filtered rows.

Answer 1

Not very clear but the following does return 90:
=sumifs(larger!D:D,larger!A:A,"A",larger!C:C,"GREEN")
The parts in quotes may be substituted by cell references.
Assumes ColumnHeader1 is in ColumnA.