Code to copy:
--------------

---------------------------------------------------------------
(ParameterName as text) =>
let
	ParamSource = Excel.CurrentWorkbook()
		{[Name="TblParameters"]}[Content],
	ParamRow = Table.SelectRows(ParamSource,
		each ([Parameter]=ParameterName)),
	Value=
		if Table.IsEmpty(ParamRow)=true
		then null
		else Record.Field(ParamRow{0},"Value")
in
	Value

----------------------------------------------------------------
Explanation:
------------ 

Be aware: code is case-sensitive
- TblParameters: the name of your table
- Parameter: Name of the column containing your parameter (e.g. Month, Year, Product, EPM-version, ...)
- Value: Name of the column containing the value of your parameter (e.g. 2021, January, EPM-Q1, ...)

Save your function as fnGetParameter

If your parameter table is as follows: 
(don't forget to Name your table e.g. TblParameters --> create a table (Ctrl+T) and rename it --> tab table design and update table name)

Column 1	Column 2	Column 3
-----------------------------------------
Parameter	Value		Comments
Month		5		select to filter on specific month

Create a variant in your query:

	1. open the advanced query editor
	2. just after the let type a new variant name (e.g. FilteredMonth)
-----------------------------------------	

let  
    FilteredMonth = fnGetParameter("Month"),
    
    Source = xxxx (existing code)
-----------------------------------------

Afterwards you will be able to use the variant (FilteredMonth) in your query using/updating the M-code

Create a new step (filtering the Month in our case): select the month column and filter on a specific month (e.g.3).
This new line will appear in the M-code (Home tab - advanced editor

-->  	#"Filtered Rows" = Table.SelectRows(#"Inserted Month", each ([Month] = 3)),

Simply replace the month number by your variant name: here FilteredMonth
--> 	#"Filtered Rows" = Table.SelectRows(#"Inserted Month", each ([Month] = FilteredMonth)),

Now your query will be dynamically filtered using the variables in your excel table.