Compare 2 Columns On 2 Worksheets For Matches

I know there is a forumla to compare a small database to a list, but can't find it (I used to use French Excel).

Here is an example :

In a sheet, my small database :

(in two different cells)

Value1 and ValueA
Value2 and ValueB
Value3 and ValueC

etc...

In another sheet, my list :

I have a list where there's a lot of Value1, Value2... in one column, and in the next column, a lot of ValueA, ValueB....

I want to check in my list : if I have Value1, then, on the same row (next column) I have ValueA, if I have Value2, then, I should have in the same row (next column) ValueB....

And if I have Value1 and in the same row (next colum) ValueB, I want some kind of "Error" text.

Can't find this function nor (of course) the criteria to use it correctly.