In Microsoft Excel, what does the syntax range=value in the following formula do exactly? That is, what is being returned by ('worksheetA'!$C$2:$C$25="something") in the following formula)

=LOOKUP(2,1/(('worksheetA'!$C$2:$C$25="something")*('worksheetA'!$D$2:$D$25="something else")*('worksheetA'!$E$2:$E$25="another thing")),('worksheetA'!$F$2:$F$25))

Please explain. I understand the lookup command but the parameters above are not familiar to me where the ranges are being compared to values. Where in the online help will I find some information about this syntax (not the lookup function but the range=value syntax)?