Tablete pomažu protiv morske bolesti.

Tablete is the nominative plural form of tableta and it is the subject of the sentence.

• tableta = one tablet
• tablete = tablets

So the structure is basically Tablets help ...

A useful extra note: tablete can also be the accusative plural form, but here it is clearly nominative because it matches the plural verb pomažu.

Because the subject tablete is plural.

Croatian verbs agree with the subject in number:

• tableta pomaže = the tablet helps
• tablete pomažu = the tablets help

So pomažu is the 3rd person plural present form.

This is about aspect, which is very important in Croatian.

Croatian often has an imperfective/perfective pair:

• pomagati = to help, be helping, help in a general or repeated sense
• pomoći = to help in a completed, one-time sense

The form pomažu comes from pomagati, and it fits a general statement like this one: tablets generally help against seasickness.

A perfective form like pomognu would sound more like a specific completed helping event, not a general truth.

Because Croatian commonly talks about medicine or remedies as something against a problem.

So:

• tablete protiv morske bolesti = tablets against seasickness

English often prefers for in this context, but Croatian very naturally uses protiv.

So even though the English translation may use for, the Croatian structure is literally closer to against.

Because the preposition protiv requires the genitive case.

The basic form is:

• morska bolest = seasickness

After protiv, it changes to genitive:

• protiv morske bolesti

So this is not an arbitrary change. It happens because protiv governs the genitive.

Because in Croatian, adjectives must agree with the noun in gender, number, and case.

The base phrase is:

• morska bolest
  
  • adjective: morska
  • noun: bolest

After protiv, the whole phrase has to go into the genitive singular, so both words change:

• morske bolesti

This agreement is completely normal in Croatian noun phrases.

It is the normal expression for seasickness.

Literally, it means sea illness, but idiomatically it is simply seasickness.

So learners should understand it as a fixed, standard phrase, not as a strange word-for-word invention.

Not necessarily.

Pomažu means help, so it suggests that the tablets:

• reduce the symptoms,
• make the problem easier to deal with,
• or help prevent it.

It does not automatically mean cure completely.

So the sentence is softer than saying the tablets definitely eliminate the illness.

Yes. Croatian word order is fairly flexible because case endings show the grammatical relationships.

The sentence as given:

• Tablete pomažu protiv morske bolesti.

is a neutral, natural order.

You could move things around for emphasis, for example:

• Protiv morske bolesti tablete pomažu.

But that sounds more marked or emphatic. For a learner, the original order is the safest and most natural one.

Because Croatian has no articles.

So tablete can mean:

• tablets
• or the tablets

The context tells you which meaning is intended.

In this sentence, it most naturally sounds generic: tablets help against seasickness.