Translation:He will be working here until December.
Тут is slighty more colloquial.
Why isn't работать conjugated to работает since we're talking about a 3rd person singular subject?
To expand on that, будет is an auxiliary verb (forming the future tense). The auxiliary verb is conjugated, and the other verb stays in infinitive. That's the same in all languages I know.
"He will WORK in December" (will BE working)
"Er wird im Dezember ARBEITEN"
"Il va TRAVAILLER en décembre"
"El voy a TRABAJAR en diciembre"
"Han skal JOBBE i desember"
It's the same reason "be" isn't conjugated in "will be" in English. You can only conjugate the first verb in a sentence with more than one.
yes, used to denote 'to', 'up to', 'until' or 'before' a certain point in time, ДО requires genitive
I listened 3 or 4 times and heard здесь еасн time. I used to listen for a job