Second Life is exactly what it says it is. With the exception of the fact that it is virtual reality, which means you can be or do anything you want.
But it is a mirror of “real” life. There are offices there. You purchase real estate to build your residential or industrial areas, you can sell insurance, virtual products or use it as a store front to sell physical products. There is a lot of entertainment there, U2 has performed there. I know that for sure, and many other bands as well (just don’t know who). I am not a participant, but it comes up just enough on occasion that I start to wonder if I should become a member.
If you would like to know just how big it really is. Here is the Wikipedia list of businesses that have a presence in Second Life.
IE- Serious businesses, like Disney, ING Group, MTV, Universal Motown Records, etc…