HellyWelly - if you use FB on a computer via a browser (like Chrome, Firefox, Exploerer, Edge etc), you need to install the Fluff Busting Purity browser extension. It allows you to stop most of the adverts and other nonsense. Unfortunately it doesn't work if you use the FB app on a phone or tablet.
Most people use their real name on FB - it's a condition of use - but some more vulnerable people (especially teachers, police etc) will invent a pseudonym to avoid stalkers.