You don't need a PhD in Flight Attending, and you don't need certifications up the wazoo either. Good thing, because you're definitely not getting paid enough to warrant it.
Once hired by an airline, they will put you through a training program that will walk you through all necessary safety precautions, emergency evacuation procedures, CPR, first aid, and more (you may have to suck out the poison if one of those snakes decides to strike).
You also have the option of attending a training school not directly affiliated with an airline to learn the ropes in advance.
Aside from completing the training program, the only other qualifications relate to height and weight. The exact specifications vary from airline to airline, but most companies don’t want someone who is scraping their head against the ceiling or bumping passengers on the aisles with their fat rolls.
Being multilingual isn't required but it's a big plus. We're not sure how often your mastery of Swahili is going to come in handy though.