Om jag tappar bort mitt bokmärke igen, hittar jag inte sidan.

Here om means if and introduces a condition.

So Om jag tappar bort mitt bokmärke igen means If I lose my bookmark again.

A common confusion for English speakers is that om can also mean whether in other contexts, but in this sentence it clearly means if.

Tappa bort is a very common verb phrase meaning to lose or to misplace something.

• tappa by itself often means drop
• tappa bort means lose track of / misplace

So:

• Jag tappade boken = I dropped the book
• Jag tappade bort boken = I lost the book

In your sentence, it means the speaker misplaces the bookmark.

Because bokmärke is an ett-word in Swedish:

• ett bokmärke = a bookmark

For ett-words, the possessive form is:

• mitt = my

Compare:

• min bok = my book, because bok is an en-word
• mitt bokmärke = my bookmark, because bokmärke is an ett-word

Swedish usually writes compound nouns as one word, much more consistently than English.

So:

• bok = book
• märke = mark / sign
• bokmärke = bookmark

This is very normal in Swedish. English speakers often want to separate these words, but Swedish generally does not.

This is because Swedish follows the V2 rule in main clauses: the finite verb normally comes in the second position.

The sentence begins with an om-clause:

• Om jag tappar bort mitt bokmärke igen

After that comes the main clause. Since something else already occupies the first position, the verb comes before the subject:

• hittar jag inte sidan

This is called inversion.

Compare:

• Jag hittar inte sidan. = I do not find the page.
• Om jag tappar bort mitt bokmärke igen, hittar jag inte sidan.

Both are correct; the word order changes because the sentence starts with the conditional clause.

In a normal Swedish main clause, inte usually comes after the finite verb and the subject.

So:

• Jag hittar inte sidan

When inversion happens, the verb comes first, then the subject, and inte still follows that:

• hittar jag inte sidan

So the order is:

• finite verb + subject + inte

This is different from subordinate clauses, where inte usually comes before the finite verb.

For example:

• ... att jag inte hittar sidan = ... that I do not find the page

Swedish often uses the present tense for both parts of a real or likely future condition.

So:

• Om jag tappar bort mitt bokmärke igen, hittar jag inte sidan.

This is natural Swedish, even though natural English often says:

• If I lose my bookmark again, I won’t find the page.

Swedish does not need a separate future form here. The future meaning is understood from the context.

If you want to make the future more explicit, Swedish can also say:

• ... kommer jag inte att hitta sidan

But the present tense version is very normal.

Igen means again.

In this sentence it comes near the end of the conditional clause:

• Om jag tappar bort mitt bokmärke igen

That is a very natural position in Swedish. It tells us that this has happened before.

English speakers sometimes expect again to move around more freely, but in Swedish, igen often comes later in the clause, especially after the object or near the end of the verb phrase.

Sidan is the definite form, meaning the page.

• en sida = a page
• sidan = the page

The definite form is used because this is a specific page, not just any page. The speaker means a particular page they are trying to get back to.

So the sentence is not about finding just any page, but the page.

Yes. Sida can mean both page and side, depending on context.

• In a book context, sidan usually means the page
• In other contexts, it can mean the side

Here, because of bokmärke meaning bookmark, sidan is understood as the page.

Not always. In modern Swedish, a comma before the main clause after an initial subordinate clause is often optional.

So both of these are possible:

• Om jag tappar bort mitt bokmärke igen, hittar jag inte sidan.
• Om jag tappar bort mitt bokmärke igen hittar jag inte sidan.

The comma can make the sentence easier to read, but it is not always required.

No. Bokmärke can also mean a browser bookmark or saved bookmark on a computer or phone.

So the word can refer to:

• a physical bookmark in a book
• a digital bookmark in a browser

The context decides which meaning is intended. In this sentence, if the meaning has already been shown to the learner, that context will tell you which one is meant.