The ''lucky bag'' she's talking about is a fukubukuro, and it's a huge deal in japan during new year season, it's like sales, except you have no idea what you'll get in the bag
but it's guaranteed to get you '' more value than you'll normaly spend when you buy stuff directly and sometime, even stuff you'll can get only in lucky bags''
somes exemples of what you can get in japan in well know brands
https://soranews24.com/tag/fukubukuro/