Need a Help with COUNTIF/COUNTIFS with matrix table from different sheet

I need a help about Countif/Countifs

please look at the Attachments file,

i have data in sheet1, just say data about selling with item name (A,B,C,D) , Month (jan 2019-jan 2020), and selling count


what the formula in (sheet2) "B2", if i choose "A2" and "B1" with the option there,
it will give the result about countif "A2" when "B1" > 0 data from sheet1

thx for your help, sry for my bad english