I think what your looking for is the vlookup function. I've created a mockup of the scenario you spoke of in your question, I have a simple table in sheet 2:

```
ID Description
1 This is part 1
2 This is part 2
3 This is part 3
4 This is part 4
5 This is part 5
```

So on sheet 1, we can use the vlookup function to gather data from this table:

```
Enter Lookup Value :: 3
Description:: This is part 3
```

We enter the lookup value as shown above, in your case this would be N. In the cell where your description will be shown, you enter the vlookup formula. Locate the cell, click on the 'Insert Function' button and select vlookup. The formula you end up with looks something like this:

```
=VLOOKUP(Sheet1!C1,Sheet2!A2:C6,2,FALSE)
```

Where `(Sheet1!c1)`

is the location of the lookup value, `Sheet2!A2:C6`

is the data range, `2`

is your description column and `false`

is the range lookup but this can be left blank most of the time.

If you take a look at this very good article it explains everything in more detail:

http://www.howtogeek.com/howto/13780/using-vlookup-in-excel/

Hope this helps!