Episode 2 of Season 7 on Game of Thrones is called "Stormborn," which probably means we're going to see Daenerys making some moves now that she's landed in Westeros. Daenerys is sometimes called Daenerys Stormborn. But what does "stormborn" mean on Game of Thrones? It's one of Dany's many, many titles, and like the rest of them, it's significant to who she is as a character.
Dany's full title is Daenerys Stormborn of the House Targaryen, First of Her Name, the Unburnt, Queen of the Andals and the First Men, Khaleesi of the Great Grass Sea, Breaker of Chains, and Mother of Dragons. Yes, it is kind of a mouthful, but each title refers to a specific thing about her that makes her the best. It's fairly obvious where most of these titles come from. She's Khaleesi because she married Khal Drogo and now rules her own Khalasar. She's the Breaker of Chains because her main mission for a while was freeing all the slaves And she's the Mother of Dragons because dragons. "Stormborn," however, comes way before any of that. This title refers to her birth, and can be seen as a sign, if you will, that she was always destined for greatness.
In A Storm of Swords, George R.R. Martin writes,
No squall could frighten Dany, though. Daenerys Stormborn, she was called, for she had come howling into the world on distant Dragonstone as the greatest storm in the memory of Westeros howled outside, a storm so fierce that it ripped gargoyles from the castle walls and smashed her father’s fleet to kindling.
Dany is described as having "come howling into the world" as the greatest storm in memory also "howled" outside, indicating that Dany herself is the greatest storm in the memory of Westeros. So far, she hasn't disappointed, gathering followers among the fiercest warriors across the narrow sea, not to mention three fearsome dragons. In the show, she has now returned to Dragonstone, the place of her birth during this raging storm. This parallel indicates that she is about to wreak havoc on Westeros, and her first stop will probably be Queen Cersei.
In the preview for the episode, Yara says, "We have an army of fleets and three dragons. We should strike King's Landing now." Meanwhile, Mad Queen Cersei says ominously, "The Mad King's daughter will destroy the realm." Cersei may think differently, but I'm on Yara's side here. I seriously doubt King's Landing is ready for Daenerys Stormborn.