Column content = Table Name or Query Name

Remark: according to your example, you are appending tables, not merging tables.

There is no function to get the name of your table.

But there is still a way to achieve what you want. It requires a deep dive into the realms of Power Query though.

Suppose your table names are Year2015, Year2016 etcetera.

Create a table "Years". e.g. for the years 2015-2030 (you may have additional years in this table for which you have no data yet):

Table.FromList({2015..2030}, each {_}, type table[Year = Int64.Type])

(this is the entire query code, so no let..in structure).

Now create the following query that creates the required result:

let
    Source = Years,
    AddedTables = Table.AddColumn(Source, "Data", each Expression.Evaluate("Year"&Text.From([Year]), #sections[Section1])),
    RemovedErrors = Table.RemoveRowsWithErrors(AddedTables, {"Data"}),
    ReorderedColumns = Table.ReorderColumns(RemovedErrors,{"Data", "Year"}),
    AddedColumnNames = Table.AddColumn(ReorderedColumns, "ColumnNames", each Table.ColumnNames([Data])),
    ColumnNames = List.Distinct(List.Combine(AddedColumnNames[ColumnNames])),
    ExpandedData = Table.ExpandTableColumn(AddedColumnNames, "Data", ColumnNames),
    RemovedColumnNames = Table.RemoveColumns(ExpandedData,{"ColumnNames"})
in
    RemovedColumnNames

This code uses Expression.Evaluate to turn table names into tables; this function requires an environment record, otherwise the tables are unknown objects when the expression is evaluated. The keyword #sections is used to get the objects from the current environment (Excel or pbix file), which returns a record with 1 field "Section1", which in turn is a record with the objects from the current environment, including your tables.

The code is dynamic with regard to changing table structures over the years, i.e. the tables may have different columns.