Meta is often used when a higher level of abstraction is required. And meta-X often describe a "X about a X". For example, metadata indicates data describing data, meta-program would be a program that program programs, meta-joke is a joke on a joke, and... [hold your breath] this very meta site is a Q&A site about the main EE.SE Q&A site.
What is it for
It is not only used to report general bugs and issues with the website. Discussions on meta can be very general and also address issues like:
- Is that kind of question on-topic/allowed on the main site?
- Why did this question got closed?
- How should I deal with this kind of posts?
- How to rationalize usage of these specific tags?
- How to behave in this specific situation?
There a are also purely informational posts, for example:
And, sometimes, some annoucements from stackexchange staff.
Organization of stack exchange
Each stack exchange site (stack overflow, electronics, whatever, ...) has its own meta, on which subjects specific to the specific main site are discussed. But when it becomes very generic and applicable to all sites, the main meta site is actually more appropriate. And as a matter of fact, I think this very question (and also most "bugs and issues with the website", as you mentioned) should be better suited there, since it isn't only applicable to electronics.stackexchange.