This ECG shows an underlying rhythm of normal sinus rhythm at a rate of 80 / min.  There are two premature ventricular contractions (PVCs).  The sinus rhythm actually continues uninterrupted, causing a “compensatory pause”.  If you march out the P waves, you may even see hints of the hidden P waves in the ST segments of the PVCs.  The P waves that occur in the ST segments of the PVCs land in the refractory period of the ventricles, and so are unable to continue into the ventricles and cause a QRS. 

It is also permissible to call these beats “ventricular premature beats (VPBs)” or “ventricular premature complexes (VPCs)”.