How to fill cells in google sheets automatically when choosing a value from a drop-down list?

Question

Google Sheets

I have 2 tables on different sheets, on the first one I display the value of some parameter with formulas (as a result, a simple table in 2 columns), on the second I want to make a droplist of the list of these parameters (column 1 of the first table), and so that in the next cell automatically the corresponding value was substituted (column 2 of the first table).
The droplist is done in an elementary way, but how to substitute the corresponding values ​​from neighboring cells?

Answer 1

=INDEX(Sheet1!B:B,MATCH(A1,Sheet1!A:A,0))