Evaluating table data in new table

Ekaterina_, for future be more precise with expected result. It should be BASED ON SAMPLE DATA!. You provided incorrect results for Jacket, Shoes and T-shirt!

Result (with ignoring Department, just to show you how it works)

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("lZA9D4IwFEX/CumMpEUT6ajioJOJbIShwos0EGoK8fcLGyCvH0PzltObe0+eE3qM6D6KaXwgIXnWCvrxnsZ364KHhg9oMUjVkSJcsWelmuk4oFehZfeegi8InXiUSLZLZCp4QVBBK+ELGqp/2K9GqqF3rqFFCS0MhmjusZD7LOToQjtv28jxjfbwbNfXUg94PKOIk83sBT2zkhowBx8Lfu7DoYSDkcUHPyN3UTZgghmib22EuYljqDgTaVfGfJUxVJmdN0orfg==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Date of export" = _t, #"Product Name" = _t, Department = _t, Status = _t]),
    FilteredOutDelivered = Table.SelectRows(Source, each ([Status] <> "Delievered")),
    ChangedType = Table.TransformColumnTypes(FilteredOutDelivered,{{"Date of export", type date}}, "sk-SK"),
    GroupedRows = Table.Group(ChangedType, {"Product Name", "Status"}, {{"Days", each Duration.TotalDays(List.Max([Date of export]) - List.Min([Date of export])) +1, Int64.Type}}),
    PivotedColumn = Table.Pivot(GroupedRows, List.Distinct(GroupedRows[Status]), "Status", "Days")
in
    PivotedColumn

Version with Department implemented:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("lZA9D4IwFEX/CumMpEUT6ajioJOJbIShwos0EGoK8fcLGyCvH0PzltObe0+eE3qM6D6KaXwgIXnWCvrxnsZ364KHhg9oMUjVkSJcsWelmuk4oFehZfeegi8InXiUSLZLZCp4QVBBK+ELGqp/2K9GqqF3rqFFCS0MhmjusZD7LOToQjtv28jxjfbwbNfXUg94PKOIk83sBT2zkhowBx8Lfu7DoYSDkcUHPyN3UTZgghmib22EuYljqDgTaVfGfJUxVJmdN0orfg==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Date of export" = _t, #"Product Name" = _t, Department = _t, Status = _t]),
    FilteredOutDelivered = Table.SelectRows(Source, each ([Status] <> "Delievered")),
    ChangedType = Table.TransformColumnTypes(FilteredOutDelivered,{{"Date of export", type date}}, "sk-SK"),
    GroupedRows = Table.Group(ChangedType, {"Department", "Product Name", "Status"}, {{"Days", each Duration.TotalDays(List.Max([Date of export]) - List.Min([Date of export])) +1, Int64.Type}}),
    PivotedColumn = Table.Pivot(GroupedRows, List.Distinct(GroupedRows[Status]), "Status", "Days")
in
    PivotedColumn