Uneven rows separate with special characters "@" should transposed to one row

Another variant is with Power Query

Generated script

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    AddIndex = Table.AddIndexColumn(Source, "Index", 0, 1),
    IndexSeparator = Table.AddColumn(AddIndex, "Custom",
        each if [Column1] = "@" then [Index] else null),
    IndexGroups = Table.FillDown(IndexSeparator,{"Custom"}),
    RemoveSeparator = Table.SelectRows(IndexGroups, each ([Column1] <> "@")),
    GroupTexts = Table.Group(RemoveSeparator, {"Custom"},
        {{"Combined", each Text.Combine([Column1], " "), type text}}),
    KeepIt = Table.SelectColumns(GroupTexts,{"Combined"})
in
    KeepIt