Learn Dutch: Wij lunchen om twaalf uur. - We have lunch at twelve o'clock.

In English we say "have lunch", but Dutch uses a single verb for this action: lunchen. You conjugate it just like a regular verb, so "we have lunch" translates directly to wij lunchen.

Why do we use the word om in this sentence?

In Dutch, the preposition om is used to point out specific times on the clock. It works exactly like "at" in the English phrase "at twelve o'clock" (om twaalf uur).

If this lesson is about words like 's middags, how would I use that here instead of an exact time?

If you want to talk about a routine without giving an exact clock time, you simply swap out om twaalf uur for your time word. To say "We eat lunch in the afternoons", you would say Wij lunchen 's middags.

Does it matter if I use wij or we at the start of this sentence?

Both are grammatically correct! Wij is the emphasized form, which you might use if you are contrasting your lunch time with someone else's. If you are just stating a neutral fact, the unstressed form we is more common: We lunchen om twaalf uur.