Alright kiddo, so imagine you have a group of people who want to fight for a cause or a country. They are not part of the official army, but they still want to help. These people are called "volunteers" because they are choosing to do this without being forced to.
Now, sometimes these volunteers come together and form what is called a "corpo truppe volontarie" or "volunteer corps" in English. This is just a fancy way of saying a group of volunteers who are organized and fighting together.
These volunteer corps can be very helpful because they are usually made up of people who are very passionate and dedicated to the cause. They may not have as much training or experience as the official army, but they make up for it in their enthusiasm.
However, there can also be some downsides to these volunteer corps. Since they are not part of the official army, they may not have as much support or resources. They may also be seen as less trustworthy or reliable than the official army.
Overall, a corpo truppe volontarie is just a group of volunteers who come together to fight for something they believe in. It can be a powerful force, but it also has its limitations.