It means ‘key’ and it’s a French word. Man, do you need to learn a few languages to know your music or what… If we have notes on a stave without a clef, we wouldn’t know which notes they are. Depending on the clef, the first line (the lowest one) of the stave could represent the Es, Gs, Cs, Fs or Ds and what’s more, on different octaves. Now, that would be troublesome, right? Not to mention that if we don’t have a clef, a composition could be interpreted in all sorts of different ways, as not all natural notes (aka. the white keys on a piano keyboard) are equally apart from one another and we would have different starting points. So we use the clefs to indicate which notes are written down.
When we draw a G clef, we start from about its center and do the spiral thingy, then we go up and draw the loopy thingy and finally we go straight down and draw the squiggly thingy. So if the G clef starts off from the second line (counting from bottom up), that means that the second line represents the G note that’s above the middle C. There are more than one G clefs, so, I know… *mind blown*. The other -less usual- G clef starts from the first line.
Similarly, the most common F clef starts off from the fourth line of the stave. It has an almost spiral shape (it ends right after when you’re about to start drawing an ear instead of a clef) and has two dots to its right. The lower dot is located in the third space while the upper dot is located in the fourth space of the stave. Now, in the cases where the F clef starts from the fourth line of the stave (and the fourth line passes between of the two dots), this line represents the F below the middle C. Let me give you another *mind blown* moment -that’s only if you find this as interesting as I do-. There are a total of 3 F clefs. From the most common to least common: the one starting from the 4th line, the one starting from the 3rd line and the one starting from the 5th line of the stave.
Finally, the C clef. It kinda looks like the letter ‘B’. Let’s think of the C clef that starts from the fourth line of the stave. The point where the two semicircles touch is skewered by the fourth line. This line represents the middle C. This is the fastest one, I promise. There are a total of 5 different C clefs, one for each line of the stave. See? Done. *sigh*