Questions & Answers about Рано утром петух стоит у забора, а свинья уже ест.
Рано утром is a very common Russian expression meaning early in the morning.
- рано = early
- утром = in the morning
So Russian builds this idea with two words rather than one fixed adverb.
You may also see ранним утром, which also means early in the morning, but it is built differently:
- рано утром = more neutral, very common in everyday speech
- ранним утром = slightly more descriptive/literary
Both are correct.
Утром is the instrumental form of утро (morning).
Russian often uses parts of the day in the instrumental case to mean at/in that time:
- утром = in the morning
- днём = in the daytime / during the day
- вечером = in the evening
- ночью = at night
So рано утром literally works like early, in-the-morning.