Translation:There have been problems between the two.
here 'ter' is an auxiliar verb, like - tem chovido, temos trabalhado, tenho lido( it has been raining, we have been working, I have been reading). Ter (informal) is used instead of haver meaning 'exist': tem uma pedra no caminho instead of Há uma pedra no caminho = There is a stone on the way. - corrected by Davu: There is a stone on the path.
I ran out of allowable layers of comment so I add here to respond to Davu: I was insisting on the subject being plural and still do: "problemas"... why isn't that so? (I was translating from English in this case and on this basis I went for têm). Your explanation worked for me (still does =D) if the Brazilian way of using "ter" has appropriated that of "haver", i.e. tem works the same way as há (dissociated with the subject). Then my answer was wrong , and your original answer would be right. Are you saying that my original translation should have been right and Doulingo's answer might not be? I'm pretty sure that I still missed something. I also want to say Thank You for what I've learnt from you beyond Portuguese!
@gaih "I ran out ..."
I agree it is slightly confusing, but the two languages work differently. From an English point of view: pietvo is quite correct; Duolingo's translation is correct; you are correct.
Now let's think about the Portuguese: you translate both "There is a stone on the path" and "There are two stones on the path" using "há". That is we use the third person singular present tense of "haver" in both cases.
You translate both "There was a stone on the path" and "There were two stones on the path" using the third person singular past tense of "haver" which, depending on context, is "houve" or "havia".
So it goes for other tenses. You can translate the (admittedly uncommon) sentences "There has been a stone on the path" and "There have been two stones on the path" with the third person singular of the compound past tense "ter havido" which is "tem havido".
There is one small "gotcha" to complicate matters and that is "tem havido" implies a sense of continuity or iteration or habit which is possibly not adequately captured by "There has/have been".
@antlane "an information ..."
The two languages work differently. In the English sentence "there" acts as a sort of dummy subject, and is basically a placeholder for "problems". It is possible to rejig the sentence to get a similar sentiment without using "there": "Problems have existed between the two" which makes it clearer that "problems" is the true subject. This works even better with your example, and "There is a stone on the path" is just another way of saying "A stone is on the path".
I was wrong. I didn't pay enough attention to how "tem" is being used here and my answer misrepresents what is going on because this isn't a simple case of using "ter" instead of "haver".
The form "ter + past participle of verb" is a tense in its own right (called "pretérito perfeito composto"). One thing I said is relevant: "haver" when it means "there to be" (for example, "there is/are") is conjugated as third person singular in all tenses (really it is not associated with a subject at all; it is impersonal a bit like "chover" - you wouldn't say "I rain" or "they rain"). That is the real reason why "têm havido" is incorrect, because that would imply a plural subject.