What applies when you see this traffic sign?

You answered correctly. In this situation, you are entering a built-up area (as shown by the yellow town sign). Here, you may choose any lane suitable for your direction of travel, and you may also drive in the right lane faster than cars in the left lane if traffic allows. However, you must always respect the speed limit in built-up areas (normally 50 km/h unless signposted otherwise), so driving faster than 50 km/h is not allowed just because there are multiple lanes. This is a common situation when entering cities where lane choice is flexible, but urban speed limits still apply.