Beginner: Knife slightly rusted - what do I do?

Hey guys, please be kind, I'm just a beginner regarding knives/sharpening

Since I take good care of my personal knives, I've never had any issues (rusting etc.). So even though I'd consider myself as decent regarding sharpening I have no experience regarding rust or similar. However, I discovered that the knife I gifted my parents has been through some abuse (photos attached) which I want to fix. I have a set of shaptons (320, 1000 and 5000). Do you have any recommendations regarding this? (E.g. should I buy a rust eraser and if yes which one?) Thanks in advance!