This is a sixteenth note. At a fixed tempo, it is played twice as fast as an eighth note or four times faster than a quarter note. We could say therefore that two sixteenth notes equal one eighth note.
There are sixteen sixteenth notes in one bar of * time.
In this example the hi-hat plays sixteenth notes.
This example introduces a rhythmic variation to the bass drum.
Sixteenth notes are introduced into the bass drum rhythm of this example.
The next example contains the same bass drum rhythm as the previous one but changes the hi-hat rhythm to eighth notes.