It seems that the word tolk (and the verb tolka) in Germanic languages come from old Slavic tlŭmačĭ, these words originated during our intense trade connections with Slavic-speaking peoples. (In German, it's Dolmetscher/in, same origin).
For those learning english, from swedish.
In swedish it may use the preposition "mellan" which is "between" But it should translate to the english preposition "for" EX: (She's an interpreter for Spanish and English speakers.) or (She translates or is a translator for French.)