Scotch is a short name for whiskey made in Scotland. Scotch must be aged in oak barrels.
A swatch is a small piece of something, usually so you can check the color of the swatches against colors in your house. When you have decided which swatch you like, you can buy a larger quantity of it. Swatches usually relate to fabrics.
A watch is something you can use to tell the time on. Watches are small and usually have a strap on, so you can wear them around your wrist. Large watches that you hang on the wall are called clocks.
It is useful to know the time, so you know when to go to school, or have dinner, or watch your favorite TV show.