On your selected frame, there are two ways that you can view the size of the frame:
1. Clicking through the frame images
2. Scrolling down at the middle of the page, and you will see the FRAME DIMENSIONS, as shown below:
The method of expression commonly used is known as the boxing system and the numbers are generally written the same way regardless of the brand of glasses.
Based on the image above, the numbers from the FRAME DIMENSIONS are translated as such:
47 = Lens Width
15 = Bridge Width
139 = Temple Length
33 = Lens Height
These numbers are also printed inside of one of the frame's temple legs. All numbers are expressed in millimeters (mm).