The resistors $R_1,R_2$ and $R_e$ will provide the biasing for transistors. $C_{c1}$ and $C_{c2}$ are coupling capacitors and $C_e$ is bypass capacitor.

The transistor is connected in the CE configuration, ∴ it introduces a phase shift of 180 degree between its i/p and o/p

The feedback network = 180-degree phase …