Note the "leis" (linn, libh, e.t.c. depending on the person) is very important otherwise it means:
An mbuaileann sibh gach Satharn é? = Do you punch him every Saturday?
I think "An mbuaileann sibh gach Satharn é? = Do you hit him every Saturday?" would be a slightly better translation, no? It's a little more general than a punch. That is, it could be a slap, for example, yes?
Oh yes, it is more general than punch, it's more that that is the image a native speaker will get if you say my sentence.
However, indeed, "buail" has the more general meaning of "hit".