It would be really nice if the site had a "Glossary of terms". I have no idea what a roll back is for example. I don't see it in the faq and it isn't the only term I've run into that I would have looked up if there was a Glossary. I've also earned an "association bonus" and am curious what that is or how that happened.
Most of the general terminology is explained in the faq, however....
The Stackexchange network originated (I believe) with Stackoverflow.com, which is a community specific to programmers. As a result, some of the terminology used on the platform tends towards the technical side.
The term "Roll back" is related to the concept of having multiple "revisions".
In order to track these changes, each post (whether a question or an answer) uses a "version" system, with each edit tracked separately, so that you can see the entire history of changes.
This can be seen by clicking on the link indicating that the post was edited:
Each revision of the post gets its own number, starting with the original version as "1". The most recent versions will be displayed at the top.
The term "roll back" simply refers to selecting an earlier version and making it the current version. You will see this option as a link to the right of the version number for each revision.
Regarding a general glossary... most of the general terminology is explained in the FAQ. Many of the individual SE sites will have glossaries on their meta sites explaining terms specific to that site (such as scifi.se's list of common abbreviations). If we find that there are a number of terms and/or abbreviations used on our site, it might be helpful to create a similar post.
If you could list some of the other terms you didn't recognize, we can either explain them here, or possibly find an existing source that explains them.
+1 to Beofett's explanation of what a rollback is.
As for the glossary, you did exactly right: ask here on meta. Whenever anything is unclear, please post a meta question.
Each such question will get a (hopefully!) useful answer, and all those questions and answers will turn into a glossary that reflects the concerns of this specific site.