VLookup table array from another sheet - vba

Question

Ive a sheet in which a cell value to be dynamically changed based on the cell value in the same row. So we have to pick that cell value first and then use that value to search in another sheet. Here is the code I have got. The sheet I have to search is Mapper
ActiveSheet.Range("P2").Select
formularwcount = ActiveSheet.UsedRange.Rows.Count
ActiveCell.FormulaR1C1 = "=VLOOKUP(RC[-11], Mapper!C[-13]:C[2],3,FALSE)"
In this code they are using R1C1 convention which I didnt understand what they mean by putting Mapper!C[-13]:C[2] there as the table array. Im only a 10 days old developer with VBA. Anyone please tell what does that mean.

Answer 1

I found this information by Googling "R1C1":
Cell References
In place of a named cell, an alternative approach is to use a cell (or grid) reference. Most cell references indicate another cell in the same spreadsheet, but a cell reference can also refer to a cell in a different sheet within the same spreadsheet, or (depending on the implementation) to a cell in another spreadsheet entirely, or to a value from a remote application.
A typical cell reference in "A1" style consists of one or two case-insensitive letters to identify the column (if there are up to 256 columns: A–Z and AA–IV) followed by a row number (e.g., in the range 1–65536). Either part can be relative (it changes when the formula it is in is moved or copied), or absolute (indicated with $ in front of the part concerned of the cell reference).
The alternative "R1C1" reference style consists of the letter R, the row number, the letter C, and the column number; relative row or column numbers are indicated by enclosing the number in square brackets. Most current spreadsheets use the A1 style, some providing the R1C1 style as a compatibility option.
Source: Wikipedia: Spreadsheets