Swept wing and airflow
Wing is sensitive to the airspeed vector which is normal to the leading edge.
For the sake of explanation airspeed over the surface of a swept back wing can be considered as a force vector which is made up of two components.
One component perpendicular to the leading edge and one across. By triangle/vector law of addition these two components/vectors can be joined by one single resultant, which is bigger than both the vectors.
Since the wing is swept back, the component of airspeed perpendicular to the leading edge becomes smaller in magnitude than the resultant (Resultant here is the relative airflow which passes parallel to the longitudinal axis).
Hence a swept back wing can go faster as compared to an equivalent straight wing without the hazard of formation of shock waves.