There are a number of threads within this forum (more on the older side now) that you can search for to find that. Best way to find an explanation, is if you have joined a guild in game, is to ask your guildmates. Some guilds even have threads listing all the various terms to help their newish players out - and I suggest in-guild to be a better way, as if you have follow up questions or more detail needed, you can ask and should get a reply right almost right away - whereas on a forum like this, you could get a reply in minutes, hours, or even not at all.
Even if you have not joined a guild yet - go ahead and join one, just for some of the basic start up help - and if you want something different, you can always jump to another guild easily enough - no issues with that, especially for a newish type player.