|Let's start by making sure we use the correct terminology.|
This wording - column A of WB 1 - has no meaning.
A workbook does not have Columns. A workbook has worksheets (at least 1) and the worksheets have columns.
So my first question is: Do you have 2 workbooks or 2 worksheets?
The answer to this will make a difference in the way the VLOOKUP formula is written. If you have 2 workbooks, you'll need to include the workbook name and worksheet name in the formula (which Excel can do for you). If not, you'll just need the worksheet name.
As per the help files for VLOOKUP, the syntax is as follows:
VLOOKUP(lookup_value, table_array, col_index_num, [range_lookup])
lookup_value: In your case, this would be the values in Column A of the worksheet where you want to populate Column B.
table_array: This will be the table, both columns A and B, of the worksheet that has the data you are "pulling from".
col_index_num: This is the column number of the table_array from which you want the data pulled once it finds the lookup_value in Column 1 of the table_array.
Keep in mind that the col_index_number is the column number of the table_array referenced in the formula, not the physical column number in the worksheet.
For example, if your table_array consisted of Columns A:D, a col_index_number of 3 would refer to Column C. However, if your table_array consisted of Columns F:H, a col_index number of 3 would refer to Column H.
[range_lookup] can be either TRUE (or 1), FALSE (or 0) or omitted, in which case it will default to TRUE.
Even though the [range_lookup] argument is optional with a default of TRUE, I recommend always using a [range_lookup] value to avoid any confusion. In most cases this argument will be FALSE (or 0) since in most cases we are trying to find an exact match. The TRUE (or 1) argument is certainly useful, it just doesn't get as much use in my experience.
So, generically, your formula might look like:
=VLOOKUP(A1, SHEET1!$A$1:$B$2600, 2, 0)
If placed in Sheet2, this will look up the value in Sheet2!A1 in Sheet1!A1:A2600 and return the value in Column B of the same row in which the value was found.
If you have values that aren't found, VLOOKUP will return #N/A. You can eliminate this by using an IF(ISNA( )) statement. This will produce a blank cell if the value in A1 is not found:
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