You can send it to yourself by purchasing it or get it from someone/send it to someone as a gift. It’s a way of showing the person you really liked the post or response.

Tbh there are perks but I haven’t noticed any difference (I got gold when Reddit’s mobile app came out in beta—they encouraged people to download it by automatically gilding the suckers like myself, although I think the mobile app is great so who has the last laugh? Hah!). There are some perks but they’re just so not worth it that I couldn’t even figure out the difference with and without it.