The head of a note indicates its position, on the staff. When the note head is below the middle staff line the stem points upward and when the head is above the middle line the stem points downward. A note placed on the middle line (B) can have its stem pointing either up or down.
This is a quarter note.
A quarter note lasts for one beat.
In most music, bar lines are drawn across the staff, dividing the music into sections called bars or measures. A double bar line signifies the end of an important section of music, while a final bar line is written at the end of a piece.