From what little is shown of the impending encounter, it appears the Mother of Dragons is sitting in her rightful place in the throne room at Dragonstone, the ancestral stronghold of House Targaryen, which she just returned to after her family's exile.
As she sits, poised and unwavering, Jon is welcomed into her castle. As King of the North, he is trying to bring together the seven kingdoms of Westeros to do battle together against the terrifying might of the White Walkers.
The stakes are even higher for Jon as Daenerys's castle is built atop a mountain of Dragonglass, which is one of only two things known to man that can effectively kill White Walkers for good.
The meeting is especially exciting for viewers who believe the fan theory that Jon and Daenerys are destined to join forces and rule Westeros together -- hence the name George R. R. Martin gave to his Game of Thrones series, A Song of Ice and Fire. Snow (aka "Ice") and the Mother of Dragons (aka "Fire") joining as one to rule all.