This is a sixteenth note. It lasts for one quarter of a beat. There are four sixteenth notes in one beat. There are 16 sixteenth notes in one bar of * time.
When counting 16th notes, notice the different sound for each part of the beat – one ee and ah, two ee and ah... etc (written 1 e + a, 2 e + a... etc). Sixteenth notes are only dealt with briefly here. For a more in-depth study, see Progressive Blues Lead Guitar Technique, or Progressive Funk and R&B Guitar Method.
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.