Hello Luiz,
This "has/have been" structure is generally used when you're talking about a situation that started in the past, and is still true now. It can also be used to talk about something that has always/never been true. Instead of a huge grammar lesson, I will give a few more examples that I hope will give you a feel for it.
Examples:
We have been married for four years. = The wedding was four years ago, and we are still married.
My mother has been sick for six months. = Six months ago, my mother got sick, and she is still sick now.
My sister has been in the bathroom for half an hour, and I need to use the bathroom! = Half an hour ago, my sister went into the bathroom, and she is still there.
This land has never been farmed. = There were no farms on this land before, and there is no farm now.
This land has not been farmed for a year. = The land was being farmed in the past. A year ago, farming stopped, and now the land is still not being farmed.
(You can add "now" to the end of the sentence like in your examples, but it is not really required since the verb tense already indicates you are talking about the situation now.)
To help with similar verb tenses, here is the same sentence but with different verb tenses, so you can see the difference:
I have been in Germany for two years. = Two years ago, I moved to Germany, and I am still in Germany.
I was in Germany for two years = I moved to Germany, then moved out of Germany two years later. I am not there now.
I had been in Germany for two years. = I moved to Germany, then two years later, something happened. Usually this type of sentence would have another part, because we expect that something happened at that time. Example: "I had been in Germany for two years when I met George." = I moved to Germany, then two years later, I met George (while still living in Germany).
I hope this helps!