Entities are deceased people, souls who passed away, but who still linger on earth. They‘re earthbound. So they are dead and their souls have left their bodies but they have not yet departed earth. They are also called spirits, ghosts, wandering souls or unwanted visitors. Entities are not by definition negative, but they can certainly cause you trouble if you are susceptible to it.
They join in with certain emotions of the host and reinforce them: active children become more active than they actually are, someone who is very emotional becomes a howler who quickly bursts into tears, and a rather unorganised person becomes a real scatterbrain.
If you have unwanted company (of spirits that is), I will make sure that they leave and help them go into the Light. Furthermore, I will help you resolve the issue, you had that attracted them in the first place, so you will not unconsciously invite similar visitors in future.