First make a copy of the database. Actually make two copies and hide one
away. If you aren't careful in doing what I say, you can destroy the database.

First off data encryption within the Access database is to keep people from
opening the database MDB file with something like a text editor or Word and
reading the raw data. Open up a copy of a MDB file having tables that is not
encrypted with Word. Scroll on down and you'll probably see some readable
text. Could be Social Security Numbers for example. Now open a copy of the
same database file that's been encrypted. You shouldn't see any useful data.

Here's why I said to make a backup! If without thinking you save the MDB
file as a Word, text, RTF, ect. document, it's totally trashed. Access can't
use it anymore. Seen it done before.

Now as far as Excel or another program reading the data, they certainly can
do so once you've given the Password during the connection. Access will
decrypt the data for them. You do have the database password protected or
have user-level security, don't you?