По лестнице можно спускаться безопаснее, если держаться за перила.

Because по often means along / on / via, and with this meaning it takes the dative case.

So:

• лестница = staircase, stairs
• dative singular = лестнице

In Russian, спускаться по лестнице is the normal way to say go down the stairs or descend by the staircase.

Compare:

• на лестнице = on the stairs / on the staircase as a location
• по лестнице = along/down/up the stairs as movement

So here по лестнице is used because the sentence describes movement along the stairs.

Можно is an impersonal word meaning it is possible, one can, or sometimes it is allowed.

In this sentence, it means something like:

• one can go down the stairs more safely
• it is possible to descend the stairs more safely

There is no specific subject like я, ты, or мы. Russian often uses можно + infinitive to make a general statement or recommendation.

So:

• можно спускаться = one can descend / it is possible to descend

This is a very common question because several related verbs exist.

1. спускаться

This means to go down, to descend, or to be descending. It is imperfective, so it describes the action in a general, repeated, or ongoing sense.

That fits here because the sentence is giving general advice about descending stairs.

2. спуститься

This is the perfective partner. It means to go down successfully / to descend once, to completion.

If you used спуститься, the sentence would sound more like a single completed action, not general advice.

3. спускать

This usually means to lower something or to let something down. It normally needs an object.

For example:

• спускать флаг = to lower a flag

So in this sentence, the correct choice is спускаться because the meaning is to descend in a general way.

In this verb, -ся is just part of the standard intransitive verb meaning to descend / go down.

Compare:

• спускать = to lower something
• спускаться = to go down oneself / to descend

So the reflexive ending here does not literally mean that someone is doing something to themselves. It is simply how Russian forms this intransitive meaning.

This pattern is very common:

• открывать = to open something
• открываться = to open
• поднимать = to raise something
• подниматься = to rise / go up
• спускать = to lower something
• спускаться = to descend / go down

Безопаснее is the comparative form of безопасно or безопасный, meaning safer / more safely.

In this sentence it works like more safely:

• можно spускаться безопаснее = one can go down more safely

The comparison is implicit. It means something like:

• more safely than otherwise
• more safely than if you did not hold the handrail

Russian often leaves the second part of the comparison unstated when it is obvious from context.

Also note that Russian comparatives can often function where English might use either an adjective or an adverb, depending on how you translate it.

Because Russian often leaves the subject unstated when the meaning is general.

This sentence is giving advice that applies to people in general, so Russian uses:

• можно спускаться
• если держаться

This is similar to English you can in the general sense, or one can in more formal English.

So the implied subject is something like:

• a person
• people in general
• you, in the generic sense

Because the whole sentence is built as a general impersonal statement.

The structure is:

• можно + infinitive
• если + infinitive

This gives a broad, instruction-like meaning:

• It is possible to descend more safely if you hold on to the handrail
• Going down the stairs is safer if you hold the handrail

If Russian used если держишься за перила, that would sound more like speaking directly to you specifically:

• if you hold on to the handrail

That version is also possible in some contexts, but если держаться matches the impersonal, general style of можно спускаться very well.

Держать means to hold something.

But держаться за means to hold on to something, often for support or balance.

So:

• держать книгу = to hold a book
• держаться за перила = to hold on to the handrail

This is a fixed and very common expression in Russian. In the sentence about stairs, держаться за is exactly the natural choice because the idea is physical support and stability.

With держаться за, Russian normally uses за + accusative.

So:

• dictionary form: перила
• after за: still перила

This verb-preposition combination is idiomatic:

• держаться за руку = hold someone’s hand
• держаться за стену = hold on to the wall
• держаться за перила = hold on to the handrail

Even though за has many meanings in Russian, here it is simply part of the standard pattern держаться за + accusative.

Перила is one of those Russian nouns that is normally used only in the plural.

It refers to a railing / banister / handrail structure, and Russian treats it as a plural noun, similar to how English has words like stairs or scissors that are often plural in form.

So:

• nominative: перила
• accusative: перила

That is why the sentence says за перила, not a singular form.

Yes, Russian word order is flexible, but the given order sounds natural and clear.

The sentence:

• По лестнице можно спускаться безопаснее, если держаться за перила.

puts the setting first:

• По лестнице = on/down the stairs

Then the main statement:

• можно спускаться безопаснее = one can descend more safely

Then the condition:

• если держаться за перила = if one holds on to the handrail

Other word orders are possible, but they may shift emphasis. For example:

• Если держаться за перила, по лестнице можно спускаться безопаснее.

This emphasizes the condition first: if you hold the handrail...

So the original order is not the only possible one, but it is very natural for giving advice.

Because если introduces a subordinate clause meaning if.

Russian normally separates subordinate clauses with a comma, including clauses introduced by:

• если = if
• когда = when
• потому что = because
• хотя = although

So the comma before если is standard Russian punctuation.