The hammer-on is executed by picking a note and then hammering a left hand finger onto the string. The hammer-on is indicated by a curved line and the letter "H".
Begin by playing the note on the 5th fret, fourth string.
Hammer third finger onto 7th fret of fourth string.
Once you are comfortable counting sixteenth notes on one note, apply them to the pentatonic scale, and then try the following pattern, which will help your picking technique.
Here is an exercise to help you develop the use of hammer-ons.