MS Excel Lookup function is one of the powerful lookup and reference functions, it is used when you need to look in a single row or column and find a value from the same position in a second row or column.
When using it you need to consider the following;
1- The LOOKUP_VALUE: which is the value we want to search in one row or column
2- The Table Array: refers to a range of cells that contains organized data in rows and columns.
3- COL_INDEX_NUM: refers to the number and order of the Column in the table array NOT in the whole Excel Sheet.
4- Range LOOKUP: specify TRUE if you want an approximate match or FALSE if you want an exact match of the return value. If you don't specify anything, the default value will always be TRUE or approximate match.
1- MS Support