The answer can be found in the Help files, simply type any of them into VB, then click on them and press F1.
In a nutshell:
The Open options basically specify whether you want to be able to "move around" the recordset or not (eg: rs.MovePrevious) rather than just forwards, and whether updates from other users are shown (after a .Requery).
The Lock options basically specify if changes can be made to the data, and how to deal with edits by other users for the same data.
It is a good idea to use the right options for your situation (use the Help to find out which), as it not only makes things faster, but also reduces the chances for issues with other users who are using the same database.