It's Slavic.

[ she imagines he'll know what that is considering what he does know about earth. she has a feeling 'sokovia' isn't a country he knows. ]

It's my first language. [ she touches her nape. ] I didn't expect it to be able to pick up any other languages.

[ she smiles. the plant doesn't stop singing to itself, seemingly happy with its song and company. ]

Now you know you have multilingual plants.