PQ question - change rows to columns

After loading your table, you can insert this step where Source is your previous step

= Table.FromRecords(List.Transform(Table.Split(Source, 3), (x)=> Record.FromList(x[Column2], x[Column1])))

The sample code in action here

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WCi4pTUnNK1HwS8xNVdJRclSK1YlWcs4vLSpOVQjJLMkBC0JEXRJLUhU8i4tLU1OAgoYG+oZG+kYGRiZgSTRznLCZ4+SExRwTfUNDnMY4YzPG2RmHc8DmmGIzxwWbOS4u+MwxVoqNBQA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t]),
    Result = Table.FromRecords(List.Transform(Table.Split(Source, 3), (x)=> Record.FromList(x[Column2], x[Column1])))
in
    Result

If you are looking for a complete point and click solution, below is one which use Pivot feature

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WCi4pTUnNK1HwS8xNVdJRclSK1YlWcs4vLSpOVQjJLMkBC0JEXRJLUhU8i4tLU1OAgoYG+oZG+kYGRiZgSTRznLCZ4+SExRwTfUNDnMY4YzPG2RmHc8DmmGIzxwWbOS4u+MwxVoqNBQA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t]),
    #"Added Index" = Table.AddIndexColumn(Source, "Index", 1, 1, Int64.Type),
    #"Divided Column" = Table.TransformColumns(#"Added Index", {{"Index", each _ / 3, type number}}),
    #"Rounded Up" = Table.TransformColumns(#"Divided Column",{{"Index", Number.RoundUp, Int64.Type}}),
    #"Pivoted Column" = Table.Pivot(#"Rounded Up", List.Distinct(#"Rounded Up"[Column1]), "Column1", "Column2"),
    #"Removed Columns" = Table.RemoveColumns(#"Pivoted Column",{"Index"})
in
    #"Removed Columns"

Hi Anonymous 

= #table(List.FirstN(Source[Column1],3), List.Split(Source[Column2],3))

Stéphane