Hey,
I’m trying to do the exact same thing an the sumifs function in excel but I don’t really know how to.
I have found that it does work like that:

Sequence of two “Math Formula” nodes:
First one: Multiply the two columns using the expression Col1*Col2 and
Append a new column.
Second one: Use COL_SUM on the new column.

Is there any example for this nodes? I need some help please

to use math formula node you need to convert the values that you want to calculate to decimal using a “String to Decimal Node” then you can use them in “Math Formula Node”.

KNIME offers multiple ways to deal with this. I have created 2 solutions. Using Joiner with Row Filter node as @izaychik63 said or Refrence Row Filter node.

In both cases you only need GroupBy node if there is multiple same products in your Product Data. Otherwise you do not have anything to sum and you do not need GroupBy node.

For SUMIF() instruction is following:
Sequence of two “Math Formula” nodes:
First one: Append new column with if(criteria, column to sum ,0)
Second one: Use COL_SUM on the new column

Considering you are using SUMIFS() function above instructions do not apply.