。
She works as a volunteer interpreter at the international conference.
Literal
She [topic-は] that international-conference [at-で] volunteer [genitive-の] interpreter [as-として] is-working.
~として ('as, in the capacity of') marks the role being filled. 通訳 ('interpreter, interpreting') is the verb-noun for live oral translation, distinct from 翻訳 ('written translation'). ボランティアの通訳 attaches the loanword ボランティア to 通訳 with の, building 'volunteer interpreter' — the noun-modifying-noun via の is the standard frame for compound roles. 国際会議 ('international conference') is a typical setting for volunteer interpreters in Japan, where multilingual events draw on enthusiastic but unpaid language helpers.