Garbage value is a value which is not useful to your program. Normally when you create a variable and don't initialize it, it has a garbage value which is left behind by another program at that memory address.
VB uses namespaces not packages, Java uses packages. Just different name but same meaning. namespaces/packages are used to organize your program, an example would be to create a package for connecting, querying a database and then using that package in your program where necessary.