Is it possible to Ungruoup one column into 3 columns using get & transfrom

Joanna,

Let do step by step. Here is the script and sorting file based on your initial sample. Initially I tried to avoid any coding and use only UI to generate the script, but very short manual combining of formulas splitting and sorting through the list makes things much easier - we don't depend on number of dots in Articles.

This part is commented:

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    DefaultTypes = Table.TransformColumnTypes(Source,{{"Article", type text}, {"Description", type text}, {"Value", Int64.Type}}),
    DuplicateArticles = Table.DuplicateColumn(DefaultTypes, "Article", "ArticleCopy"),
    SplitArticles = Table.SplitColumn(DuplicateArticles, "ArticleCopy",
        Splitter.SplitTextByDelimiter(".", QuoteStyle.Csv), {"Article.1", "Article.2", "Article.3"}),
    LevelsToNumbers = Table.TransformColumnTypes(SplitArticles,
        {{"Article.1", Int64.Type}, {"Article.2", Int64.Type}, {"Article.3", Int64.Type}}),
    AddLevel1 = Table.AddColumn(LevelsToNumbers, "Custom1", each if [Article.2] = null then [Description] else null ),
    FillLevel1 = Table.FillDown(AddLevel1,{"Custom1"}),
    AddLevel2 = Table.AddColumn(FillLevel1,
        "Custom2", each if [Article.3] = null then
            if [Article.2] <> null then [Description] else ""
            else null),
    FillLevel2 = Table.FillDown(AddLevel2,{"Custom2"}),
    AddLevel3 = Table.AddColumn(FillLevel2, "Custom3", each if [Article.3] = null then "" else [Description] ),
    RemoveTempColumns = Table.SelectColumns(AddLevel3,{"Value", "Article", "Custom1", "Custom2", "Custom3"}),
    ReorderColumns = Table.ReorderColumns(RemoveTempColumns,{"Article", "Custom1", "Custom2", "Custom3", "Value"}),
    RenameColumns = Table.RenameColumns(ReorderColumns,{
        {"Custom1", "Group"},
        {"Custom2", "sub-group"},
        {"Custom3", "Description"}}),
    ProperColumnsType = Table.TransformColumnTypes(RenameColumns,{
        {"Article", type text},
        {"Group", type text},
        {"sub-group", type text},
        {"Description", type text}
    }),

    // Here we convert each Article into the list, like
    // "3.2.11" => {"3","2","11"}
    ArticelToList = Table.AddColumn(ProperColumnsType, "Custom", each Text.Split([Article],".")),

    // Next by Text.PadStart add zeroes to the start of each list element to have totally 4 symbols
    // and transform it into one text string, like
    // {"3","2","11"} => {"0003","0002","0011"} => "000300020011"
    ListToSortString = Table.TransformColumns(ArticelToList,
        {"Custom", each Text.Combine(List.Transform(_, each Text.PadStart(_,4,"0")), ""), type text}),

    // Sort by this column and remove it then
    SortAscending = Table.Sort(ListToSortString,{{"Custom", Order.Ascending}}),
    AndRemoveIt = Table.RemoveColumns(SortAscending,{"Custom"})
in
    AndRemoveIt

File is attached.

Please not your resulting table is sorted by PowerQuery on each refresh if only you set External Table properties (right click on it and check menu) as this