The current copy is really unclear, "Pick your languages"... for what?
Copy ideas:
"Choose preferred language"
"Preferred search languages"
"Quick search languages"
"Preferred Wikipedia languages"
Alternative we add a "What does this do?" sub header (as on the "Whats New" onboarding slide) and a modal popup explaining. Something like this, but shorter/better:
"Your first choice language will be used as your search language, and articles will load in that language. Any additional lnaguages will be placed at the top of languguge choices, so you can easily swtich between them when searching or reading an article."