The SUICA IC card is a pre-pay card you can use in Japanese metropolitan areas for most buses, trains, and subways as well as in some stores. The "IC" stands for "Integrated Circuit" or "Integrated Chip" as the card contains an embedded chip that remembers your balance.
This page describes two pre-pay cards: PASMO and SUICA. In most metropolitan areas these cards are interchangeable. For this trip you will get a SUICA card with ¥2,500 already on it.
There is a home page for SUICA here. Wikipedia has a pretty comprehensive article on SUICA.
Or, you save it for your next trip to Japan: just top it off at a train station or selected stores and you're good to go.