From Wiktionary, the free dictionary
Contraction of не бо́йся (ne bójsja, literally “do not fear”).
небо́сь • (nebósʹ)
- (colloquial) I suppose, most likely, probably, I dare say
У вас там небо́сь снег идёт.- U vas tam nebósʹ sneg idjót.
- I suppose it's snowing there at your place.
- (colloquial) sure, no fear
Небо́сь, не замёрзнешь!- Nebósʹ, ne zamjórznešʹ!
- Don't worry, you won't get frostbite!