Под ногами тихо шуршит сухая листва.

Because под can take different cases depending on the meaning:

• под + accusative = movement to under something
  
  • положить под стол = to put under the table
• под + instrumental = location under something
  
  • лежать под столом = to lie under the table

In Под ногами тихо шуршит сухая листва, there is no movement to a place. The leaves are already rustling underfoot, so Russian uses the instrumental:

• под ногами = under the feet / underfoot

So под ноги would suggest motion toward that position, which is not the idea here.

The base noun is нога (leg, foot depending on context). Here Russian uses the plural ноги because the expression means under one’s feet in a general sense.

After под in a location meaning, the noun goes into the instrumental case:

• ноги → ногами

So:

• под ногами = under the feet / underfoot

This is a very common idiomatic expression in Russian.

Russian often leaves this unstated when it is obvious from context.

• под ногами usually just means underfoot
• if needed, Russian can specify:
  • под моими ногами = under my feet
  • под его ногами = under his feet

In a descriptive sentence like this one, the general expression sounds natural and elegant. English often also does something similar with underfoot.

Листва is a collective noun. It refers to foliage or a mass of leaves rather than to individual leaves one by one.

So although the real-world meaning involves many leaves, grammatically листва is treated as a singular feminine noun.

That is why you get:

• сухая листва — adjective in feminine singular
• шуршит — verb in 3rd person singular

Compare:

• листья шуршат = the leaves are rustling
• листва шуршит = the foliage / the mass of leaves is rustling

Both are possible, but листва sounds more literary and atmospheric here.

Because листва is grammatically:

• feminine
• singular

Adjectives must agree with the noun in gender, number, and case.

So:

• сухая листва = feminine singular nominative

If the noun were листья (leaves, plural), then the adjective would be plural:

• сухие листья

Because the subject is листва, and листва is grammatically singular.

Russian present-tense verbs agree with the subject in number (and in the past tense, also gender).

So:

• листва шуршит = singular
• листья шуршат = plural

Even though there are many leaves in reality, the noun листва behaves like a singular mass/collective noun.

Yes, шуршит means rustles, makes a soft dry brushing sound, or whispers softly depending on context.

The verb is шуршать, an imperfective verb often used for repeated or continuous rustling sounds:

• бумага шуршит = the paper rustles
• листва шуршит = the leaves/foliage rustle

It is a sound-symbolic word, so it strongly evokes the actual sound.

Here тихо is an adverb, so it means quietly, softly, or faintly.

It describes how the rustling happens:

• тихо шуршит = rustles softly

Russian тихо can sometimes also function more generally like it is quiet, but in this sentence it clearly modifies the verb.

Russian word order is flexible, and changing the order changes the focus or feel rather than the core meaning.

Starting with Под ногами puts the scene first:

• Под ногами тихо шуршит сухая листва.
  • first sets the location: underfoot
  • then gives the sound and image

This makes the sentence feel more descriptive and atmospheric, almost like a camera shot beginning from the ground.

A more neutral order would be:

• Сухая листва тихо шуршит под ногами.

That is also correct, but the original sounds more literary.

No. The subject is сухая листва.

A good way to see this is by looking at agreement:

• листва is singular feminine nominative
• the verb is шуршит, singular
• the adjective is сухая, matching листва

Meanwhile, под ногами is a prepositional phrase showing location: underfoot.

So the structure is roughly:

• Под ногами = location
• тихо шуршит = predicate
• сухая листва = subject

Yes, that is a very natural translation.

Depending on style, you could also say:

• Dry leaves rustle softly underfoot.
• Dry foliage rustles softly underfoot.
• Underfoot, dry leaves rustle softly.

The Russian листва is a little closer to foliage or leaf litter / mass of leaves than to plain leaves, but in normal English dry leaves is often the best natural translation.

It is in the nominative case, because it is the subject of the sentence.

You can tell from the form:

• dictionary form: листва
• in the sentence: сухая листва

Both the noun and adjective are in nominative singular feminine.

Yes. In the present tense, Russian normally does not use a separate word for is/am/are in sentences like this.

So Russian simply says:

• листва шуршит = the foliage is rustling / rustles

The verb шуршит already carries the meaning of the action, so no extra is is needed.

Yes, slightly.

Nothing in it is unnatural, but the combination of:

• листва instead of the more everyday листья
• the fronted phrase Под ногами
• the sound-focused verb шуршит

gives it a descriptive, scenic, literary feel.

In everyday speech, someone might more simply say:

• Под ногами шуршат сухие листья.

That sounds a bit more straightforward and conversational, while the original sounds more atmospheric.