Powershell to count cells in one column based on filter value

Powershell to count cells in one column based on filter value

My excel spread sheet has 11028 rows, and two columns.
First column has organizational unit, and second column has value.
In Excel, I can filter the first column so that there are about 100
different organizational units. And for each organizational unit, I want
to count (1) total number of rows (2) number of rows with value "Unknown".
If I do this manually, it will take forever, hence I am looking for some
sort of API in powershell that will allow me to count number of rows in
column B based on filter set in column A.
Is this even possible in Powershell?