Guitar music is often written in two parts, with both parts played by the same musician. You can compare it with a duet, where two different parts are written on two staves. In classical guitar arrangements, the two parts are written on one staff.
The first (top) part is usually the melody. Its stems point up while the stems of the second (bass) part point down. Both parts are counted simultaneously, as shown in the previous example. The two dots at the end of the staff before the double bar lines are called a repeat sign and mean that you play the exercise again from the start. This style of part writing is similar to choral or orchestral music, where each musician needs to be able to read and count their part individually. In this case, the melody part is played rest stroke with the fingers and the bass part is played free stroke with the thumb.
The easiest way to begin playing two part music is to play whole notes in the bass, as shown following example. Take it slowly at first and practice the melody and bass separately if you need to.