Getting count of values from a column

hi chunyong 

Based on your sample data, it is possible.

Try this:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WKjVU0lFKSSxJBFLFJUWZeemGOhDaCEobgxQYKsXqABUbYSpWgDJMkZQZoyszgZqFrMgEXZE5kqQphkXIzjDD5WZTHTTXxAIA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Index = _t, #"Col A" = _t, #"Col B" = _t, #"Col C" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Index", type text}, {"Col A", type text}, {"Col B", type text}, {"Col C", type text}}),
    #"Duplicated Column" = Table.DuplicateColumn(#"Changed Type", "Col B", "Col B - Copy"),
    #"Split Column by Delimiter" = Table.ExpandListColumn(Table.TransformColumns(#"Duplicated Column", {{"Col B", Splitter.SplitTextByDelimiter(",", QuoteStyle.None), let itemType = (type nullable text) meta [Serialized.Text = true] in type {itemType}}}), "Col B"),
    #"Changed Type1" = Table.TransformColumnTypes(#"Split Column by Delimiter",{{"Col B", type text}}),
    #"Grouped Rows" = Table.Group(#"Changed Type1", {"Col B"}, {{"Data String Count", each Table.RowCount(_), type number}, {"Details", each _, type table [Index=text, Col A=text, Col B=text, Col C=text, #"Col B - Copy"=text]}}),
    #"Expanded Details" = Table.ExpandTableColumn(#"Grouped Rows", "Details", {"Index", "Col A", "Col C", "Col B - Copy"}, {"Details.Index", "Details.Col A", "Details.Col C", "Details.Col B - Copy"})
in
    #"Expanded Details"