A dot placed above or below a note tells the musician to play the note staccato. Staccato means to play a note short and separate from other notes. Listen to example 16 on the CD to hear the effect of staccato.
The way a note is played is called the articulation. Legato and Staccato are examples of different articulations.
This example contains both staccato and slur marks. Again, follow the written music as you listen for the different articulations.