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=vlookup({{range in current sheet}},IMPORTRANGE("{{url of matching sheet}}","{{Sheet Name}}!{{columns to be matched}}"),{{number of the column for which the value should be returned}},false)
eg: =vlookup(E:E,IMPORTRANGE("http://example.com", "Sheet1!E:E"),1,false)
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=ARRAYFORMULA(VLOOKUP(C123&" "&D123,{'Feature HELENCPQ'!$G$2:$G$620&" "&'Feature HELENCPQ'!$H$2:$H$620,'Feature HELENCPQ'!$I$2:$I$620},2,false))
Well that's a vlookup of an array with 2 cells merged in a 'Ghost' cell made to be compared with another cell which btw is in another sheet.