Expression.Error: We cannot convert the value "Manual_inbound" to type Function.

Hello antalgu 

the error is in your Table.TransformColumns. This function nees a nested list with your columnname as string and a function. Both is missing. So to fix this your code should look like this

Table.TransformColumns(Table.SelectRows(_CanviTipoTrucada, each ([Campaña] = "Manual_inbound")),{{"DDI_Entrante",each "Manual_inbound"}}),

And by the way i would choose another aproach to change the content of you column "DDD_Entrante".

Instead of Transforming you table 3 times by applying a SelectRows-function each time and probably combine them afterwards again, i would suggest you to us a Table.ReplaceValue. This would look like this (not complete, just to give you an idea)

Table.ReplaceValue(_CanviTipoTrucada,each [#"DDI_Entrante"],each if each [Campaña] = "Manual_inbound" then "Manual_inbound" else if ........, Replacer.ReplaceText, {"DDI_Entrante})

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Kudoes are nice too

Have fun

Jimmy