i.e. I need to make a cell in worksheet show the same value, as summary of my Pivot Table?
Generally, you can just click into the cell in the pivot table you want to summarize. For a grand total it should generate a formula that looks like this:
This assumes the field you're summarizing is called "data values" and that the top left cell of the pivot table is located at Sheet2!$A$1.
If this type of formula isn't automatically generated, you need to activate the "Generate GetPivotData" feature. See this Contextures page for instructions.
GetPivotData is more complex if you are summarizing subtotals or individual items. You can use variables in the formulas, which makes it quite powerful.