This is an eighth note. It lasts for half a count. There are eight eighth notes in one bar of * time. When eighth notes are joined together the tails are replaced by one beam.
The following example shows a constant stream of eighth notes played on the snare drum. Alternate the hands RLRL and then reverse them (LRLR). Once you can do this strongly and evenly at a reasonable tempo, play the example with one hand at a time (RRRR etc and LLLL etc). Once again, remember to count out loud as you play.
The next important step in gaining control of eighth notes is to play them on the hi hat and ride cymbal with the right hand as demonstrated in the following example. It is important to keep the notes even and the sound consistent.
Once you are comfortable playing eighth notes with the right hand, try adding the backbeat on the snare drum with the left hand.
The following example uses the bass drum in conjunction with the constant eighth notes played by the right hand.