I basically know that Frühstück, Mittagessen and Abendessen are common in Germany. However, I am interested to know how brunch is called in German language. Can we use zweites Frühstück for brunch? Or is there any specific name for it?
"Zweites Frühstück" is usually for people who start working very early and need another meal between their early breakfast and lunch.
In school, I had breakfast at home a 6.30 am, zweites Frühstück at 10 am during the first longer break in school ("Große Pause") and lunch at 1 pm.
"Brunch" is used in German language. When I was younger, I didn't know the word brunch. My family used to call it "spätes Frühstück".
Brunch is a special kind of meal. It's the combination of breakfast and lunch.
If a restaurant offers a brunch, I expect a mixture of breakfast and lunch. So there would be typical breakfast food (bread rolls, butter, jam, honey,...) but also typical lunch items (warm meat, potatoes, vegetables, ...).
If a restaurant offers a second breakfast, I expect a normal breakfast. The breakfast could be smaller than a normal breakfast, because the landlord expects, that I already had a breakfast at home.
A second breakfast is normally just a repetition of a breakfast. Or it is a prepared bread and butter sandwich for a break. A bakery could advertise their pastry/cookie as a second breakfast (you can buy it and eat it immediately as a snack).
I think the fitting german expression for "zweites Frühstück" would be "Vesper". Brunch is the Combination of Breakfast and lunch, and is used in this way in german. So no, i would say "vesper" to the second breakfast.
This is very common in manual labour jobs. They start early, around 6 in the morning, already had their breakfast, then around 9 its the "vesper", at noon its the "mittagessen"/Lunch and then they go home at 4 to have "Kaffee". And a Dinner in the evening.
The second breakfast could in some parts of germany be called "Brotzeit" (southern area).