Always, eternally, until the end of time, at any time, or used as an intensifier.
We use ever to mean always it is usually preceded by the preposition for giving us the for ever, which can also be spelt forever. In British English for ever is used to mean until the end of time whereas for ever and forever are both used to mean a for a long time. In American English only forever is normally used for both meanings.
For example: I hope life will be like this for ever. (eternally)
This bus is taking forever to come. (a long time)
We use ever to mean "at any time in the existence of". It has the opposite meaning to never. I haven't ever is the same as I have never.
For example: Have you ever visited Poland? (at any time) No, never. Yes, I went in 1989.
Has a man ever been to the centre of the Earth. (at any time during the existence of man)
We also use ever as an intensifier normally in the phrase ever so. It just adds intensity to the expression and means very.
For example: That is ever so interesting. (very interesting)
You have ever such a lovely house. (very lovely)
I have eaten ever so much food. (very much)