Hi, TravelMom, I understand the train system can be confusing so no worries about starting a new thread to cover just Germany.
Basically the Eurail covers trains only; with some exceptions. The easiest way to find out is at the Eurail site, which has a list of each country covered by the pass that details what the pass covers in that particular country. Just scroll down and click on the link. https://www.eurail.com/en/plan-your-trip/trip-ideas/trains-europe/useful-train-information/participating-railway-companies
In Germany, it will cover everything that is listed in the link above. If you want something that covers local transport within a city; i.e., bus, tram or metro, you can either subscribe to a Deutschland ticket (commonly called the D-ticket) that allows you to travel on regional trains in German (including Salzburg and Kufstein in Austria and Schaffhausen in Switzerland) but will also cover local public transport within each city (except Salzburg and Kufstein in Austria and Schaffhausen in Switzerland). :-)
So what you need to do is figure out whether the cost of the D-ticket (€58 each month) is worth it. A lot depends on how many people are in your family (children under 6 are free, but everyone else needs their own ticket), how long you will be in Germany and in what cities/towns you will be staying. It might be easier and cheaper to just pay as you go. Many cities in Germany, such as Munich, are very walkable and you might not need public transport as much. I was in Berlin for a week, and didn't use public transport that much as I walked whenever I could. So I would try to do the math as much as possible.
To be honest, I don't think it would be worth it, since your Eurail pass would cover the train travel that you would get with the D-ticket. So you really you would only be using it within the city for public transport. But again, I would do the math. There is also the additional chore of having to cancel the D-Ticket by the correct date so that you do not continue to be charged for it. It's not that much of a hassle, but it is something to think about that you have do.
EDIT: Just an FYI, most major cities in Germany and in Europe have their own travel card for public transport. For example, you can find one for Berlin by visiting this website: https://www.berlin.de/en/public-transportation/1772016-2913840-tickets-fares-and-route-maps.en.html Some will be geared for tourists, and these usually include public transport plus entrance to many major sites. One example is the Berlin Welcome Card. The easiest way to find these is to visit a particular city's tourism website and there should be information about that. Or you can come back here and ask specific questions (in the relevant forum) about each city's options for public transportation and whether there is a travel card.