Learn Russian: В саду тихо. - It is quiet in the garden.

This lesson teaches that nouns describing a location usually take an -е ending in the Prepositional case. However, a small group of short, masculine nouns take an irregular -у (or -ю) ending instead. Сад (garden) is one of these exceptions, so "in the garden" is always в саду. Other common examples include в лесу (in the forest) and на полу (on the floor).

Why is there no word for "it" or "is" in this sentence?

Russian completely leaves out the verb "to be" in the present tense. Additionally, when describing a general atmosphere, state, or weather, Russian does not use a "dummy" subject like the English "it". You simply state the condition itself.

Why does тихо end in -о instead of an adjective ending?

Тихо is an adverb. In English, we use an adjective to say "it is quiet". But in Russian, when you describe a general environment without a specific noun as the subject, you must use an adverb ending in -о.

Does the word order matter here? Can I say Тихо в саду?

Тихо в саду is grammatically correct, but В саду тихо is much more common. Russian naturally puts the location first to "set the scene" before describing the action or atmosphere happening there.