Eller hur literally means 'or how'.
It's used at the end of a sentence and is roughly equivalent to saying 'right?', or 'isn't it/doesn't it/don't you think) – basically you're seeking confirmation from the listener. But when you use eller hur?, you're almost always expecting agreement, so it's a rhetorical question.
If you're genuinely wondering if what you said is correct, you should add eller? to the end of your statement instead, but in this case, you would usually change the word order of your statement, just like in a normal question. Compare the two sentences: Tycker alla om kaffe, eller? (Does everyone like coffee, or…?) and Alla tycker om kaffe, eller hur? (Everyone likes coffee, am I right?). If someone said the first example, it's more of a genuine question, so someone might respond Nja, jag föredrar te (Well, I prefer tea); you could simply ask tycker alla om kaffe? but adding eller? makes it clear you want a response. Someone who said the second example would be intending it as a rhetorical question.
An alternative to eller hur? is inte sant? (literally 'not true'). These kinds of phrases, added onto a statement to turn it into a question, are called question tags in linguistics, and in English they are complicated because they change based on the question, for example: 'he's Swedish, isn't he?', 'you're Swedish, aren't you?', 'you aren't Swedish, are you?' 'you moved to Sweden, didn't you?'.
As you can see, in English tag questions, the subject (in this case, 'he' or 'you') usually matches the subject of the phrase, and the verb needs to agree with the subject and tense of the verb (aren't/didn't). If the statement is positive, the tag question will be in the negative form (he is Swedish, isn't he), and if the statement is negative, the tag question will be positive (he isn't Swedish, is he?). It can be a headache for English language learners, many of whom opt to use 'yes?' as a question tag instead. In fact, you'll often hear Swedish speakers add 'or?' to statements, inspired by eller?, because it's simply snappier. Stay in Sweden long enough, and even native English speakers might pick up this habit!
In Swedish, eller?, eller hur? or inte sant? can be added to any statement to turn them into a question, without any agreement or conjugation. This is similar to 'right?' or 'correct?' in English; the two differences are that 'right?' can be used both for genuine and rhetorical questions, and that English 'right?' is generally informal and 'correct?' is formal. You can use eller? and eller hur? in most contexts in terms of formality, but as described above, eller? is mostly used for genuine questions and eller hur? for rhetorical ones.
You can also use eller hur on its own as an emphatic response, expressing your agreement. For example, if someone says kanelbullar är så goda! (cinnamon buns are so tasty), you can reply Eller hur?! (Right?!) as an alternative to another emphatic agreement, like ja, absolut! (yes, absolutely!) In this sort of situation, eller hur sounds much more colloquial and natural.
Vi borde åka på semester tillsammans.
We should go on holiday together.
Det var en jättebra film.
That was a great film.
It was, wasn't it!