Since when is obiad not considered lunch anymore? I remember learning it as lunch before.
the official dictionary definition of 'obiad' (and also how we consider it) is 'a hot meal being eaten usually in the middle of a day'. thus we can consider it both as lunch or dinner, depending what time exactly it is eaten (around midday or more in the afternoon, e.g. around 5pm afterwork).
so, as long as it is rather big, hot meal eaten in between the breakfast and supper (or other afternoon/evening tea/snacks) we name it 'obiad'. It is more about the form than the time actually :)
Do nouns like lunch (obiad) always add -em if they're at the end of the sentence, or is there another reason obiad becomes obiadem?
Unfortunately, the end of the sentence doesn't have anything to do here. "Przed" (before, in front of) simply takes Instrumental*. Instrumental endings for masculine singular will mostly have ending -em or similar (see here for more details).
So for example:
before breakfast - przed śniadaniem (neuter)
before lunch - przed obiadem (masculine)
before dinner - przed kolacją (feminine)
*In most cases. To be more precise:
(+ instrumental) before (earlier than in time)
(+ instrumental) in front of (denotes location)
(+ accusative) in front of (denotes movement)
Both of them , Lunch and Dinner should be consider as OBIAD. Usually polish people do not eat meal while work time.
I mean that in the type what you hear you don't know whether she says pije or piję (tho it's always the ę form)
Ja nie piję, On, Ona Ono nie pije.
That is difference. Is not possible to hear, in normal speech.
I am begging please explain me the whole cases thing I want to understand it PLEASE EXPLAIN THE WHOLE CASE THING TO ME PLEASE