A vibe is an energy someone has. You can tell if someone is happy, sad, angry and many other emotions just from the "vibe" they give out.

'Vibe' refers to 'vibrations'. We feel vibrations of a person when we interact with him. These vibrations may be positive or may be negative according to that person's perspectives about us. If he has some ill-thoughts about us, we feel bad vibrations despite his sweet words and vice versa. "Feel a vibe" or "Get a vibe" generally refers to positive vibrations.

'Vibe' refers to 'vibrations'. We feel vibrations of a person when we interact with him. These vibrations may be positive or may be negative according to that person's perspectives about us. If he has some ill-thoughts about us, we feel bad vibrations despite his sweet words and vice versa. "Feel a vibe" or "Get a vibe" generally refers to positive vibrations.

Often you can say you "get a good vibe" or you "get a bad vibe" from someone. It basically means after meeting them, or chatting to them, that you get a feeling that the person is very nice or not nice at all. This is usually a first impression based on not much, normally just a type of gut instinct. Hope that makes sense.