This is Variegated Arrowhead Vine (Syngonium podophyllum 'Albo-variegatum') in the Arum Family (Araceae).
The amount of variegation can vary and It looks like your plant has developed entirely white, non-chlorophytic leaves and stem.
Plant tissue without chlorophyll cannot manufacture sugars (food) for the plant through photosynthesis. it can only survive by taking food from another part of the plant.
It would be fine for a large plant with multiple stems to have a few all-white leaves , but you don't want all of the plant's new growth to be without chlorophyll. You should cut of that stem off all the way back to the point that it stops being green. This will encourage the base of the plant to produce a new stem. Hopefully one that is partly green.