What does a jet engine do

Looked all over the internet and can't find a simple, general, easy-to-understand answer. Does the jet engine simply just propel the airplane to go at super-fast speeds? Thanks in advance

A jet engine is more generally called a turbine engine. It consists of a compressor section, a combustion section, and a turbine section; as well as the inlet and exhaust.

The compressor section consists of a number of fan and compressor blades called stages. These blades spin and progressively compress the air more and more. The more the air is compressed the more energy can be extracted

Once the air is compressed it is mixed with fuel and burned in the combustion chamber. Unlike a four-stroke reciprocating engine, the air flows through the engine continuously and the combustion is continuous as well. No source of ignition is needed once the engine is running.

The hot exhaust gasses stream out of the back of the engine at high speed and provide thrust; but on their way out, the exhaust gas first passes through the turbine section. The force of the exhaust gasses turn several stages of turbine blades. The turbine blades are connected to the compressor blades through one or more shafts, making the compression-combustion-turbine cycle a self-perpetuating cycle.

Modern engines are called turbofans because some of the compressed air from the first stage of compression go around the core of engine bypassing the combustion chamber, and come out the back. In this manner the first blade or several blades, called fan blades, act the same way as propellers would on a propeller-driven aircraft. These engines may be classified as low-bypass or high-bypass depending on how much air flows around the combustion chamber instead of through it. Newer high-bypass engines are more fuel efficient, and you will notice that engines on newer passenger airlines appear larger than older engines because of the larger bypass duct.