I read HMC476MP86 Datasheet.
Is "0603 Pkg" the same meaning as "0.0236inch × 0.0118inch"?Or does "0603 Pkg" mean "0.6 mm x 0.3 mm"?Can I also do the same interpretation about other parts?
0603 Pkg means that the size of the device is 60 mils by 30 mils.
Yes, you can follow the same for other parts.
Gerber files for the EVB can be found on the product page, which also contain the sizes of the component pads on the PCB.