A magnetic coil is a coiled up piece of metal that has been magnetized. That being said, a magnetic coil is often a temporary magnet, meaning that is does not last for a extensive period of time.
Magnetic coils are the result of an an electrical current being shot into it. The movement of the the electrical current is what causes a magnetic field, thus giving the coil magnetic properties. The magnetic properties usually do not have a significant use. These sort of coils are plainly used to transfer energy from one source to another inductive source. The magnetic field aids in the transferring process.
A magnetic coil is often used in machinery do to its ability to transfer energy. It may be asked why a single string of inductive material could be used. The answer to this is that when an electrical current is shot into one string, the resulting magnetic field is weak. However, each loop in a coil contributes to the magnetic field, which makes it stronger. As aforementioned, the magnetic field aids in the distribution of energy.
Another question may be asked is why use a temporary magnet rather than a permanent magnet. Temporary magnets provides limited energy on its own and a lot on our part. Permanent magnet provides significant energy and requires no energy to induce. It seems logical we use permanent magnetic coils. However, there is one big advantage for electromagnetic coils, AKA magnetic coils. This advantage is the power to manipulate the magnetic field. This is done by through changing the intensity of the electrical current. We cannot do this with permanent magnets as they are are electromagnetic.