That is the diameter and the width of the wheel in inches. Keep in mind those measurements are from the bead seat.
For your car, go with a 17x7 +45mm to 50mm offset with 215/50-17 tires. I felt that 215/50-17 tires on my 2000 Camry were a very good compromise between ride and performance. There are also a lot of tires to choose in this size.
If money is a concern, go with 17s. The wheels and tires will be less expensive and may save gas.
Good rims I suggest.... BBS RGR, BBS RS-GT, Volk RE30 are some good ones. Maybe BBS forged Mg RE
Here was my car on 17x7 with 215/50-17 tires