The example above contains 4 measures. The 4/4 at the beginning of the tab designates that each measure contains 4 beats.
The first measure (after the 4/4) contains only 2 notes. These notes (2 draw and 3 blow) are both half notes and each are played for 2 beats.
The second measure in this example begins with 4 eighth notes. Notice that the eighth notes are tied together. Eighth notes receive only 1/2 beat, therefore it would take 8
eighth notes to fill an entire measure. In this measure though the 4 eighth notes are followed by 2 quarter notes that each receive 1 beat. The count on the second measure
would be as follows: 1 and 2 and 3 4.
The third measure contains 4 quarter notes. Each quarter note receives one beat so this is a much simpler measure to play that the previous one.
The final measure in the example is a whole note. A whole note receives 4 beats so you hold it for the entirety of the measure.