As you can see from the picture, the racket (or padel) is a solid racket that is generally foam filled with graphite or fibre glass on the outside. The holes are for aero dynamics for one - making it easier for the padel to be swung - but also generally act in the same way as strings do on a racket. . . the more holes (strings) the more control - the less number of holes the more power. The stiffness of the foam also makes for a different experience with the padel. The softer the foam, the easier to hit, but less control and visa versa. 

The padel is around 45cm long with varying shapes - round, teardrop or diamond. They are approx 26cm wide and 3.8cm thick!