Translation:We would often get books from our parents.
I think it's because of the aspect difference between “dostat” and “dostávat.” Here “dostávali” means that we kept getting books, or that we got books over and over again. DL expresses that in English by “would.”
I am not sure of the difference to “we often got,” or whether such a sentence is even grammatical in English. (Edit: BoneheadBass says it is – thanks.)
I am by no means an expert in Czech, but... I think there is a Czech convention that the possessive need not be specified with family relationships and body parts, and that personal "ownership" is assumed when a possessive is not used.
So my thought would be that, in the sentence you asked about, an explicit possessive might be required, to indicate that it's the students' parents to whom the headmaster is referring.
But an authoritative answer from one of the CZ natives on the team would be great, in case I'm totally wrong!
To me, as an ESL speaker, were getting does not couple well with often.
Note that there is NO direct correspondence between English simple and progressive tenses and Czech aspect. Mechanically translating one aspect with only progressive or simple (and vice versa) will lead to nonsense sentences or grammatical mistakes.
I wonder if you could elaborate on this statement? Firstly, I don't quite understand what is meant by "aspect" yet. Secondly, it seemed to me from this section so far that the best translation of this sentence to indicate its real meaning would be "... we were often getting...." which is both a valid statement in English and shows clearly the ongoing action, even if not quite so common a way of expressing the activity. However it seems from the discussion that is not the case. Thirdly, what is an ESL speaker? Thanks.