Yes there is a part for you to enter all your spoken languages. Be sure to list Afrikaans as that is actually pretty unique to med school applicants unlike nearly everything else anyone does lol. I would read your application just like it says, it helps but it's not necessary. I wouldn't learn a language just to be able to get into med school, but if Spanish or any other language interests you go for it.
I consider myself "conversant" in Spanish and I have a degree in it. I wil be the first to caution you though; it wasn't what I expected. I expected to take Spanish classes to help me speak Spanish better, but instead nearly every 3-400 level course is some form of Spanish literature. I mean it makes sense in retrospect; noone majors in English to learn how to speak English. Spending some time (at least ~2-3 months) in total immersion (i.e. moving to a different country) is the best thing you can do to improve your speaking abilities.