Learn Hardcore Russian: Лестница узкая, но я иду по ней спокойно. - The staircase is narrow, but I walk up it calmly.

In the present tense Russian usually omits the copula “to be.” So instead of saying “The staircase is narrow,” you just say Лестница узкая, literally “Staircase narrow.”

What grammatical case are лестница and узкая in, and why?

Both are in the nominative singular feminine. Лестница is the subject of the first clause, and узкая is its predicate adjective; predicate adjectives agree with their nouns in gender, number, and case, so they both appear in the nominative.

Why is there a comma before но?

Но is a coordinating conjunction linking two independent clauses (“Лестница узкая” and “я иду по ней спокойно”). In Russian, you put a comma before но when it joins full clauses just like in English.

What is the difference between the conjunctions но and а?

Both can mean “but,” but но expresses a stronger contrast or exception (“the staircase is narrow, but I’m still walking calmly”). А often just marks a gentle contrast or shift in topic, more like “and/but on the other hand.”

What does the preposition по indicate here, and why not на?

Here по + dative case means movement along a surface or pathway. Идти по лестнице means “to walk along/up/down the staircase.” With на you would express location (“on the staircase”) rather than movement along it.

Why is the pronoun ней used after по, and why not неё?

After по you need the dative case. The feminine singular dative form of она (“she/it” for a feminine noun) is ней. Неё is the genitive or accusative form, which doesn’t go with по here.

What is the tense and aspect of иду, and why not хожу?

Иду is present tense, imperfective, unidirectional (motion in one direction, actually more like continuous “I am going”). Хожу is also imperfective but multidirectional or habitual (“I go [habitually or back and forth]”). Since you’re describing a single ongoing action, иду is correct.

What part of speech is спокойно, and why is it placed at the end?

Спокойно is an adverb modifying иду (how you walk). Russian word order is flexible; placing спокойно at the end gives a natural, relaxed feel, emphasizing the manner of walking.

Can the word order be changed, and how would that affect emphasis?

Yes. For example:

Я спокойно иду по узкой лестнице. (More neutral, introduces “I” first.)
По узкой лестнице я иду спокойно. (Emphasizes the narrow staircase.)
Спокойно я по ней иду. (Emphasizes your calmness.)
Moving words around shifts the listener’s focus but doesn’t change the basic meaning.