A metal match, aka firesteel, is often confused with flint and steel. It is similar to the flint used in a cigarette lighter, but much bigger.
Most metal matches are made from a mixture of metals and rare earth elements. The mixture is alloyed at a high temperature and then shaped into rods of various diameters. The rods can be scraped with any piece of hard metal to produce long, hot sparks.
To use a metal match, place it in the center of your tinder, and while holding it firmly in place with one hand, use the opposite hand to strike it with your knife blade, using a firm yet controlled downward stroke at 90 degrees. The resulting spark should provide enough heat to ignite the tinder. this may take several attempts. If after five tries, it has not lit, rework the tinder to ensure that adequate edges are exposed and oxygen is able to flow through it.