I think what you have there is Dieffenbachia 'Sterling,' It is also known as also known as "dumb cane" or "mother-in-law plant."  It needs bright indirect light to keep healthy.  If it gets too much sun, the leaf edges will turn brown.  If it doesn't get enough, it will get leggy and you will lose the lovely bushiness it now has. Water it when the top two inches of the soil are dry to the touch, and then water it thoroughly.  Be sure not to let the pot stand in water, however. Fertilize it with half-strength houseplant  fertilizer every month during the spring and summer.  Keep it at normal room temperatures--it does not like to get cold.  A note--do not allow anyone, including pets, to ingest any part of the plant.  It will cause mouth swelling and pain.

Thank you, Alice!! :)