You can use conditional formating, with a formula like this:
=(MATCH(A2,$B$2:$B$4,0)0)
It will be true if the value on cell A2 is present in the list in B2:B4.
This can be applied to cell A2 and then copy format to the other cells.

" wrote:

I have two columns A & B. I need to first check if the Value in Column
B exists in Column A if yes then Highlight the Value in Column A.

So...

Name1 Name2
Dude Harry
Joe Sally
Bob Joe

Result:
the cell with Joe in Name1(ColumnA) should be Highlighted.