In this paper, we are concerned with some qualitative properties of the new fractional Musielak–Sobolev spaces WsLΦx,y such that generalized Poincaré type inequality and continuous compact embedding results. Moreover, prove any function in WsLΦx,y(Ω) may be extended to a WsLΦx,y(RN), Ω⊂RN is bounded domain class C0,1. addition, establish result relates complemented subspace WsLΦx,yRN. As an app...