Я вижу след на песке.

You can omit Я.

Russian verb endings usually show the subject clearly, and вижу already means I see, so Вижу след на песке is grammatical.

Including Я is still very normal. It can:

• make the sentence clearer,
• add emphasis,
• sound more natural in some contexts.

So:

• Я вижу след на песке. = neutral, explicit I
• Вижу след на песке. = I see a track on the sand, with the subject understood

вижу is the 1st person singular present tense form of видеть.

So:

• видеть = to see
• я вижу = I see

This verb is imperfective, which is why it has a real present tense.

A few related forms:

• я вижу = I see
• ты видишь = you see
• он/она видит = he/she sees

Notice that the stem changes a little: вид- becomes виж- in я вижу.

Because след is the direct object, so it should be in the accusative case.

But for many masculine inanimate singular nouns, the accusative looks exactly the same as the nominative.

So:

• nominative: след
• accusative: след

That is why the noun seems unchanged.

A useful comparison:

• Я вижу след. = I see a track.
  (след is inanimate, so accusative = nominative)

• Я вижу брата. = I see my brother.
  (брат is animate, so accusative looks like genitive: брата)

Because на is being used to show location: on the sand.

When на means location, it usually takes the prepositional case.

So:

• dictionary form: песок = sand
• prepositional singular: на песке = on the sand

This is different from motion:

• на песке = on the sand, located there
• на песок = onto the sand, movement toward it

So in your sentence, the track is already there, and the speaker sees it there, so на песке is the right choice.

Because на suggests something is on the surface of the sand.

A след is usually understood as a mark on the sand, so на песке is the natural choice.

Compare:

• след на песке = a track/mark on the sand
• что-то в песке = something in the sand

So на fits the idea of a visible mark on the surface.

след is a broad word. It can mean:

• trace
• mark
• track
• footprint
• trail

The exact meaning depends on context.

In Я вижу след на песке, the most natural idea is something like:

• a track,
• a footprint,
• or a visible mark in/on the sand.

So след is a flexible word, not just one exact English equivalent.

Yes: the sentence is talking about one visible mark or track.

• след = one track / one mark / one footprint
• следы = tracks / marks / footprints

So:

• Я вижу след на песке. = I see a track on the sand.
• Я вижу следы на песке. = I see tracks on the sand.

Russian, like English, chooses singular or plural depending on what the speaker wants to point out.

No. Russian word order is much more flexible than English word order.

Я вижу след на песке is a neutral, straightforward order:

• Я = subject
• вижу = verb
• след = object
• на песке = location

But other orders are also possible, with different emphasis:

• На песке я вижу след. = emphasizes on the sand
• След на песке я вижу. = emphasizes the track
• Я на песке вижу след. = possible, depending on context

So the given sentence is the most neutral and beginner-friendly version, but not the only possible one.

The stress is:

Я ви́жу след на песке́.

So:

• ви́жу — stress on the first syllable
• песке́ — stress on the last syllable

A rough pronunciation guide:

• Я ≈ ya
• ви́жу ≈ VEE-zhu
• след ≈ slyed
• на песке́ ≈ na pyes-KYE

That English-style guide is only approximate, but the stress pattern is important.

Russian has no articles like a, an, or the.

So след by itself can mean:

• a track
• the track

The difference comes from context, not from a separate word.

In isolation, Я вижу след на песке could be understood as either:

• I see a track on the sand
• I see the track on the sand

English has to choose an article, but Russian usually does not.

Because вижу is the imperfective present form and means I see.

увижу is from the perfective verb увидеть, and it means I will see or I will catch sight of.

Compare:

• Я вижу след на песке. = I see a track on the sand.
• Я увижу след на песке. = I will see a track on the sand.

A key point in Russian:

• imperfective verbs can have a present tense
• perfective verbs normally do not have a true present tense; their “present-looking” forms usually refer to the future

So if the meaning is happening now, вижу is correct.