A connecting conjunction can be used to create a compound sentence, or turn a bunch of boring sentences into a short quick list, which sounds much better than stating the same thing over and over again.
An example of a list wihtout coordinating conjunctions:
Tia is on the volleyball team. So is Taylor. Indigo is also on the volleyball team. Jessica is on the volleyball team as well.
Basically it can connect words, phrases, or sentences.