chickpea,
Not sure I can help with this since the Reiki I practice is very traditional and doesn't use new age types of vocabulary and explainations.
She is probably talking about some sort of 'energy' shift, likely to a 'higher' vibration.
I always take these things with a grain of salt.
As for the taking one to an 'upper world' I have no idea you should ask the practitioner about this (and the energy shift) to understand what they mean. Not everyone uses the same 'dictionary' when it comes to these things. (meaning that one person's 'rose' could be another person's 'skunk'

)