Если на ладони царапина, лучше наклеить пластырь.

In Russian, the verb to be is usually omitted in the present tense.

So:

• Если на ладони царапина
  literally feels like: If on the palm [there is] a scratch

This is completely normal Russian. English requires there is / there’s, but Russian often leaves it out when the meaning is clear.

A fuller version would be:

• Если на ладони есть царапина... = If there is a scratch on the palm...

That is also correct, but the version without есть is very natural.

Because на can take different cases depending on meaning:

• на + accusative = movement onto something
• на + prepositional = location on something

Here the meaning is location: the scratch is on the palm, not moving onto it.

So:

• на ладони = on the palm
• на ладонь would suggest movement onto the palm

Also, ладонь is a feminine noun, and its prepositional singular form is ладони.

Ладонь means the palm of the hand.

This is more specific than:

• рука = arm / hand
• кисть = hand (the hand as a body part, especially anatomically)
• ладонь = palm

So на ладони means specifically on the palm, not just somewhere on the hand.

Because царапина is the thing being identified as present.

In на ладони царапина, the structure is like:

• On the palm — a scratch
• or more naturally: There is a scratch on the palm

The noun naming what exists is normally in the nominative here:

• царапина = nominative singular

So the sentence is not treating царапину as an object; it is presenting a scratch as the thing that is there.

Лучше means better and is very commonly used in impersonal advice constructions.

• лучше наклеить пластырь = it’s better to put on a bandage / plaster

Russian often gives advice this way without saying it is or specifying a subject like you.

So this structure means:

• Лучше + infinitive = It’s better to...

Examples:

• Лучше подождать. = It’s better to wait.
• Лучше не спорить. = It’s better not to argue.

Because наклеить is perfective, and here the sentence refers to a single completed action: applying the plaster.

• клеить = imperfective, more like to be sticking / to stick repeatedly / in general
• наклеить = perfective, to stick on / apply as one finished action

Since the advice is about one practical action, perfective is natural:

• лучше наклеить пластырь = better to apply a plaster

This sounds more like do it and have it done.

Literally, наклеить means to stick onto or to glue onto something.

With пластырь, it is commonly used in the sense of:

• apply a plaster
• put on a Band-Aid
• stick on a bandage

So although the literal image is sticking something on, in natural English the best translation is usually put on or apply.

Here пластырь means an adhesive bandage, often translated as:

• Band-Aid
• plaster (especially in British English)

Be careful: in other contexts, пластырь can also mean a medicated plaster or adhesive medical patch.

In this sentence, the meaning is clearly the ordinary small bandage you stick over a scratch.

Because пластырь is the direct object of наклеить, and it is an inanimate masculine noun.

For inanimate masculine nouns, the accusative singular is the same as the nominative singular:

• nominative: пластырь
• accusative: пластырь

So:

• наклеить пластырь = to apply a plaster

If it were animate, the accusative form would usually match the genitive instead.

Russian often leaves the subject unstated in general advice.

So лучше наклеить пластырь really means something like:

• it’s better to put on a plaster
• you should probably put on a plaster

The person is understood from context. This is very common in Russian, especially in instructions, recommendations, and everyday comments.

Yes, absolutely.

That version is grammatically correct and maybe a little more explicit because it includes есть = there is.

Compare:

• Если на ладони царапина... = natural, compact
• Если на ладони есть царапина... = also correct, slightly fuller

Both are fine. Native Russian often prefers the shorter version when the meaning is obvious.

Yes.

The sentence begins with a subordinate clause introduced by если (if), and that clause is separated from the main clause with a comma:

• Если на ладони царапина, лучше наклеить пластырь.

This is standard Russian punctuation.

Yes, it could:

• Если на ладони царапина, то лучше наклеить пластырь.

The word то often appears in if ... then ... structures, but it is optional here.

So:

• Если..., лучше... = natural
• Если..., то лучше... = also natural, slightly more explicit

Both versions are correct.

It sounds like general practical advice.

Russian often uses this kind of structure to express a recommendation that applies in a typical situation:

• Если на ладони царапина, лучше наклеить пластырь.

That means something like:

• If you have a scratch on your palm, it’s better to put on a plaster.

It does not have to refer to one specific person unless the context makes that clear.