Adding values of two or more rows

This can be solved using the Power Query `Group By` function, aggregating the `Quantity` column using `Sum` function.

You only show a single month, and all `GSE ID`s correspond to a single `GSE`. And all the `Hrs` are identical for a single `GSE ID`. If your actual data is different, you may have to change your groupings.

Paste into the Advanced Editor changing the Source line as appropriate

let

//Replace Source line with your actual data source
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{
        {"Year", type text}, {"Station", type text}, {"Month", type text}, 
        {"GSE", type text}, {"GSE ID", type text}, {"Quantity", type number}, 
        {"Hrs", Int64.Type}}),

//Group by all the columns except Quantity
//Sum the Quantity and use some function that will only return a single item in the hours
    #"Grouped Rows" = Table.Group(#"Changed Type", {"Year", "Station", "Month", "GSE", "GSE ID", "Hrs"}, {
        {"Quantity", each List.Sum([Quantity]), type nullable number}
        }),
    #"Reordered Columns" = Table.ReorderColumns(#"Grouped Rows",{"Year", "Station", "Month", "GSE", "GSE ID", "Quantity", "Hrs"})
in
    #"Reordered Columns"

Results: