What's "fill my prescription" mean?

Native speaker’s answer
Rebecca
To "fill a prescription" means to get a(nother) dose of medicine when you receive a prescription or run out of your current prescription. For example, if you have a chronic illness and you've taken all the medicine you got from the pharmacy, you can go back to "fill your prescription." Ex: I need to go to the pharmacy and get my prescription filled. Ex: I've prescribed you some medicine. You can go to the pharmacy to get it filled.