A Whole note symbol indicates that the note should be held for a duration of 4 beats. Half notes are held for 2 beats, so they sound twice as quick. Quarter notes are held for one beat each, again twice as quick as the half notes and 4 times quicker than the whole note.
Counting is a very useful tool when learning to read or understand rhythms.
Roll over the chart to see the rhythm in action.
Click chart to hear me play along.