Holy sh*t -- the two time defending champs! That's exciting news and I hope she sticks.
It's typical for contract details to emerge a couple days/weeks later but I'd be surprised if it's guaranteed. You can only carry 6 guaranteed contracts and Vegas already has 5 on the books for this season. (
see here) I would expect them to save that spot for a more high profile signing. In my opinion the fact that Vegas offered two years is a small sign of hope that the organization is serious about her making the team. If it was a training camp contract (one year, minimum salary, non-guaranteed), it would be more of an invitation like "hey come try out for us and we'll see." She might have had other one year minimum offers from around the league (especially from worse teams where she'd likely get more serious playing time) and offering two years (and maybe a couple thousand more bucks?) was a way for Vegas to out compete those other offers.