I was working with a table with quite a few columns where the column names were using Camel Case Notation (ThisIsMyColumnName), and I did not want to rename them manually.

I used the following Power Query Code below to let it do the column renaming and putting in the space for me.

Thanks to @Excel_City for assisting me in finding the answer

https://bondarenkoivan.wordpress.com/2017/11/07/how-list-zip-helps-with-renaming-columns-in-power-query/#comment-306

This is what my table looked like with the Camel Case Notation

I then added the following code below

HeadersChange = Table.TransformColumnNames(#"Previous Step Name", each Text.Combine(Splitter.SplitTextByPositions(Text.PositionOfAny(_, {"A".."Z"},2)) (_), " "))

The only thing that I changed between different tables was the Previous Step Name, which in my example above was called #”Previous Step Name”

After putting in this step it allowed me to have my column names with the spaces as shown below.

That makes my life a lot easier and working much more efficiently.

Here is a working example of the entire code below.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSAeLYWAA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [ThisIsMyColumName = _t, ItWouldBeBetterWithSpaces = _t]),
    #"Previous Step Name" = Table.TransformColumnTypes(Source,{{"ThisIsMyColumName", Int64.Type}, {"ItWouldBeBetterWithSpaces", Int64.Type}}),
    HeadersChange = Table.TransformColumnNames(#"Previous Step Name", each Text.Combine(Splitter.SplitTextByPositions(Text.PositionOfAny(_, {"A".."Z"},2)) (_), " "))
in
HeadersChange

As always if there are any questions or suggestions please let me know.