Translation:You have a mother, sisters, and brothers.
I got the "type what you hear" exercise for this sentence and I felt that the stress on the accented vowel "ü" wasn't adequate in the pronunciation of "Brüder" (plural). For me it sounded more like "Bruder" (singular). Are native German speakers able to clearly decipher that the pronunciation is referring to "Brüder" (plural)?
It is normal for an r at the end of a syllable not to sound as such. It does however change the vowel sound. Today, the sentence sounds fine to me. R pronunciation can get quite complicated. There are regional differences. Old theater diction will sound the r at the end. You can find lots of YouTube Videos on this.
Doch is mood particle. Those are hard to explain. Essentially, it means "yes, even though it has been denied before"
It's a tricky word that can intensify or negate. It's a little like the English word "indeed." There's a good discussion of it here: http://www.slip-of-the-tongue.com/german/aber-doch-some-tricky-german-words/
The indefinite article "eine" only fits a feminine noun so a singular Bruder would need to get his own indefinite article "einen". I'd give Schwester her own article, too.
Du hast eine Mutter, eine Schwester und einen Bruder.
There is no plural indefinite article by the way. Hence, no extra articles for Brüder and Schwestern.
Is the comma correct before the und when it writing a list ? The accepted answer here https://german.stackexchange.com/questions/33191/comma-or-no-comma-before-und says never.
The serial (or Oxford) comma is optional in English but non-standard in German, although there are situations, where the comma would resolve ambiguities.
- There are commas between elements of a list (when they are of equal rank), but no comma after the last element if the sentence continues.
1.1 There are no commas if the elements of the list are interconnected by conjunctions (und, oder, sowie).
1.1.1 An exception are lists of main sentences that are connected bei conjunctions.