This symbol is called a quarter rest. It means there is one beat of silence.
When a rest comes after a note, that note must be stopped by lifting your finger off the fretboard, but not off the string. That is, the string is not pressed down against the fretboard. Keep counting even when you see a rest.
This symbol is called a half rest.
It means there are two beats of silence.
This rest is written on the third line of the staff.
How many quarter rests fit in a half rest?
Remember to use i-m. Start the following piece with m.