The F CLEF is a sign placed at the beginning of the music staff to indicate the pitches of the notes. Without a clef sign, notes on a staff have no meaning. It is the key that leads to being able to read the music.
The F clef is also called the bass clef, and some even call it the "left" clef because it usually indicates what the left hand is doing in piano music (but not always...).
When drawing this clef, the upper curve curls around the fourth line of the staff, which indicates the F below middle C. Two dots are placed above and below the same line for emphasis.
These are paper patterns for applique, embroidery, or other art projects. Each pattern purchased contains three regular, instructional pages (8.5 x 11 inches) plus one over-sized pattern page (16 x 16 inches) for the making of one block that will finish 15 x 15 inches square.