大伙儿 (dàhuǒr) is a colloquial, northern Chinese way to say 'everybody, everyone' — it's the same meaning as 大家 (dàjiā) but more casual and often used in everyday speech. It's less formal than 各位 (gèwèi) or 诸位 (zhūwèi), which are polite address forms, and less literary than 众人 (zhòngrén). The '-r' is the erhua suffix typical of Beijing/northern Mandarin.