There are three ways for a question to get a flair. The most obvious one, given that your post has it, is for the question to be a 'meta' post, which earns it an orange flair. We flair these so users can tell that it's not a regular question, that it's about the state of the subreddit. It also makes it easier to track and follow the posts.
The next, and probably the most common method, is for the question to be about the weekly theme. These get a light brown flair, helping to bring questions that fit with the week's theme to people's attention. The themes aim to broaden the variety of questions that get asked, to encourage people to ask about less common topics. However, they can have an inconsistent effect, with some themes aligning a lot more with what is usually asked about. For example, six months ago, we made the theme Ships and Shipping, which pulled in a good few questions, many of which would probably have been asked anyway as they are on common topics. When we made the theme Waterworks in September, we got no questions in the theme.
The final flair category is 'Great Question', in turquoise. These have the fuzziest set of criteria, as the flair isapplied at the choice and discretion of the mod team. As the name suggests, it is reserved for questions the team (or at least one member of it) think are especially good. Generally this means that a question has either asked something particularly insightful and interesting about a common topic, or that it has asked about a topic that comparatively rarely comes up. However, we try to keep this relatively rare, to ensure that it's not overused.
The first two flairs are largely applied by keywords by AutoModerator. This is not the most precise way of doing things, since it can often miss questions that a flair applies to but that don't include the keyword. It can also have sometimes have false positives on common words that fit the theme. If you see a question with a theme flair that shouldn't have it, or a question that should have it but doesn't, feel free to drop the modteam a modmail or put a report on the post and we'll deal with it. Great question flairs are applied manually by the modteam.
You might like reading the thread announcing the "Great Questions" flair from /u/Georgy_K_Zhukov
See also the previous meta thread Does marketing questions as GREAT QUESTIONS subtly bias which questions get answered? Does it make people feel uncomfortable because a question not marked can be implied as a average/below average question?
/u/crrpit