Here in Portugal, most display useful info like date, time, outside temperature (with varying degrees of accuracy), as well as services provided by the pharmacy or some general (often season specific) health recommendation.

The use of a bright green sign is, of course, to seek attention, but it’s also useful to quickly spot an open place at night, when most are closed and only a few remain opened longer in each town/city neighborhood (called “farmácias de serviço”, i.e something like “pharmacies in service”; they usually rotate between themselves each week). Nowadays you can check which places are available at night through a nice website, but the signs remain a useful thing, nonetheless.

The animations are just a culture thing now, I’d guess. Different pharmacies employ different animations, some wackier, some less, though there are very common animations for sure, such as the one where a 3D cross is animated rotating on multiple axis at the same time, making a nice spin back to its original position.
Why? I dunno, they break up the usual info display and help grab attention? I dunno, you get used to it and it mostly gets filtered into the background hehe