Sumifs formula with Indirect function explanation

SUMIFS(INDIRECT("'"&G$2&"'!WWytd"),INDIRECT("'"&G$2&"'!$b:$b"),$B22,INDIRECT("'"&G$2&"'!$a:$a"),G$16)

i am using this in an excel sheet to prepare a report

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The title still,technically does not follow rules.. but I will apply one in this case because if you don't know the formula, I guess it is difficult to describe the question....

Anyways,

SUMIFS, in Xl2007 and later, sums a range (the first range in the formula) based on multiple criteria based on the subsequent ranges and corresponding criteria.

The indirect function indirectly refers to a reference based on the content of a cell... e.g you must have a sheetname in G2 which you want to use to get the formula to go to the sheet of that name and sum cells in a named range called WWytd and sum based on column B entries being equal to B2 of your active sheet and column A being equal to G16 of your active sheet.