Okay, now the pieces are coming together. I think what happened is that you were just standing near a gold seller’s character while he yelled. If you type /y before a line of text, your character will shout it. That makes the text turn red and the “voice” carry farther. I’m betting the reason you saw it below your map is that the character was standing there from your perspective, and you saw the speech balloon.
Yeah, that’s the standard way gold sellers advertise. In fact I don’t remember seeing one yell before; that’s rather bold. Anyway, best thing you can do whenever you see one of those messages, yelled or whispered, is to right-click the name in your chat box and select “Report Spam.”
That’s right, Quasi. We’re in the middle of the Midsummer Fire Festival holiday. Every zone has bonfires near the towns, Alliance and Horde. Standing near the bonfire is a questgiver who has a quest named “Honor the Flame.” If you talk to that person and complete the quest, you’ll get some experience and some Burning Blossoms in your pack. If you then stand near the bonfire and right-click the Blossom, it will reignite the fire and give all the Alliance characters in the zone a buff. That’s what’s happening when you see the little fireball above your head and you jump in the air and cheer.
Now you’ll notice I said “reignite” above. That’s because the other half of the festival involves finding all the Horde’s fires and putting them out. When you do that, you’ll get some experience and all the Horde players in the zone lose their buff. Be careful when you do this, though. Extinguishing the Horde fire “flags” you for player-vs-player combat. That means that Horde players will be able to fight and kill you for a period of time.
At your level, I’d stick to honoring the Alliance’s bonfires. It’s great free experience; last year I got two levels on my mage just from doing the fires alone! You’d be surprised how far you can get just running along the roads, too, even into higher level zones like Duskwood and Stranglethorn Vale. You might die a time or two, but the bonfire experience paired with the exploration experience is worth it.
The bonfire at Sentinel Hill is right across from the flightmaster near the sawmill. Look for the big red tent. While you’re there, make sure to dance around the maypole! There’s an object called Ribbon Pole on the far side of the tent. If you hover your cursor over it, it turns into a gear. Right-click on the pole and your character will start twirling. Now, take a look up next to your map. An icon with a flame will appear - that’s a buff that gives you 10% extra experience for every creature you kill! If you dance for about a minute, you’ll get the full hour-long duration for the buff. Then when it runs out, go back and do it again!