Connect to SharePoint folder by parameters

Apple08 

I think you missed a closing bracket ")" in line number 3.

Try this

let
    Source = SharePoint.Files(Site, [ApiVersion = 15]),
    #"Filtered Rows" = Table.SelectRows(Source, each ([Extension]=".xlsx"and([Folder Path]= @Site&@PR))),
    #"Filtered Hidden Files1" = Table.SelectRows(#"Filtered Rows", each [Attributes]?[Hidden]? <> true),
    #"Invoke Custom Function1" = Table.AddColumn(#"Filtered Hidden Files1", "Transform File (2)", each #"Transform File (2)"([Content])),
    #"Renamed Columns1" = Table.RenameColumns(#"Invoke Custom Function1", {"Name", "Source.Name"}),
    #"Removed Other Columns1" = Table.SelectColumns(#"Renamed Columns1", {"Source.Name", "Transform File (2)"}),
    #"Expanded Table Column1" = Table.ExpandTableColumn(#"Removed Other Columns1", "Transform File (2)", Table.ColumnNames(#"Transform File (2)"(#"Sample File (2)"))),
    #"Filtered Rows2" = Table.SelectRows(#"Expanded Table Column1", each true),
    #"Renamed Columns" = Table.RenameColumns(#"Filtered Rows2",{{"Source.Name", "Date"}}),
    #"Replaced Value" = Table.ReplaceValue(#"Renamed Columns","Report","",Replacer.ReplaceText,{"Date"}),
    #"Replaced Value1" = Table.ReplaceValue(#"Replaced Value",".xlsx","",Replacer.ReplaceText,{"Date"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Replaced Value1",{{"Date", type date}}),
    #"Filtered Rows1" = Table.SelectRows(#"Changed Type1", each true)
in
    #"Filtered Rows1"

Thanks, it resolved the comma issue.  However no data are shown after the filters.  I have removed all filters and leaving the Souce data on, it showed all files in the SharePoint site instead of going into the folder path.  I put the PR parameter as: Documents/Report/PR Folder, I wonder have I put the paramenter incorrectly?