If the line pointing to the S is raised it might explain the look on the serif. I’m still thinking it’s from a hit, but it might be worth checking the variety sites to see if the have a match.
Hi and welcome to CT. It means exactly that. Something harder than copper hit the coin, or it was dropped onto something and damaged it.
That looks like either a "strike through error", or some kind of "double strike" on your coin. There are two parallel lines that make a clear shape. One going to the "S" mint mark, and one slightly above it. Those do not look like scratches to me. The two lines look raised. A scratch would not split the top serif of the "S" ... but some kind of strike through (Strike Thru) error, or double strike, would do it. Looks like you have a coin that has some considerable value, depending on what the rest of your coin looks like. Anywhere from a few hundred dollars to a couple of thousands of dollars. Search terms "Strike Through Coin Error" and "Double Strike Coin Error". A double strike is not the same thing as a double die. It's when the coin is struck once, and then struck again with the same die, but rotated, or, struck a second time with the die for a different coin.
One only needs to look closely at the coin, and the mint mark, to see it was hit by something. Copper is a soft metal and is easily moved. This coin has circulated considerably after being hit. All 4 digits in the date show signs of being hit. It’s flattened and the top of the 9 has raised metal from being pushed downward. Only the curve on the top left of the mint mark is normal. The remainder of the “S” is flattened. Just below the area that looks raised that split the top of S actually has raised metal showing it was scrapped. Through time, handling and circulation this has become worn but still visible. It raised a small amount of copper and forced it into the S. The coin is clearly damaged from an unknown source from the hit. Circulation had worn it down and that’s why it looks like it does. Not even close to a strike through.
