Bibliotekarien bad mig bläddra försiktigt, eftersom boken var gammal.

Bibliotekarien means the librarian. The ending -n is the definite article attached to the noun.

• en bibliotekarie = a librarian
• bibliotekarien = the librarian

In Swedish, definiteness is often shown by adding an ending to the noun instead of using a separate word like the.

Bad is the past tense of be, which here means to ask or to request.

• att be = to ask / request
• ber = asks / is asking
• bad = asked
• bett = asked (supine/past participle-related form)

So Bibliotekarien bad mig... means The librarian asked me...

Because mig is the object form of jag.

• jag = I
• mig = me

In the sentence, the librarian asked me, so Swedish uses mig.

• Bibliotekarien bad mig... = The librarian asked me...

After bad mig in this kind of structure, Swedish uses the infinitive without att.

• bad mig bläddra = asked me to leaf through / asked me to turn the pages

This is similar to English asked me to..., but Swedish often leaves out att after verbs like be in this pattern.

So:

• Hon bad mig komma. = She asked me to come.
• Han bad oss vänta. = He asked us to wait.

Bläddra usually means to leaf through, flip through, or turn pages.

In the context of a book, it suggests moving through the pages, not necessarily reading every word.

So here bläddra försiktigt means something like:

• turn the pages carefully
• leaf through the book carefully

Because försiktigt is an adverb here, meaning carefully.

Compare:

• försiktig = careful (adjective, describing a noun or person)
• försiktigt = carefully (adverb, describing how an action is done)

In this sentence, it describes how I should leaf through the book:

• bläddra försiktigt = leaf through carefully

Eftersom means because or since.

It introduces a subordinate clause that gives the reason:

• eftersom boken var gammal = because the book was old

It is a very common way to explain why something happened.

After eftersom, Swedish uses subordinate clause word order. In this sentence, that simply gives:

• boken = subject
• var = verb
• gammal = adjective/complement

So:

• eftersom boken var gammal = because the book was old

In many subordinate clauses, Swedish places sentence adverbs like inte before the finite verb:

• eftersom boken inte var ny = because the book was not new

That is a useful pattern to remember.

Boken means the book.

• en bok = a book
• boken = the book

Again, Swedish usually marks definiteness by adding an ending to the noun.

Because bok is a common-gender noun (en bok), so the adjective in this structure is gammal.

Compare:

• en bok → boken var gammal
• ett hus → huset var gammalt

So the adjective agrees with the gender of the noun.

The comma is possible and natural in writing, especially when the reason clause comes after the main clause. But Swedish punctuation is often a bit less strict than English punctuation in this area.

So both of these can be seen:

• Bibliotekarien bad mig bläddra försiktigt, eftersom boken var gammal.
• Bibliotekarien bad mig bläddra försiktigt eftersom boken var gammal.

The meaning is the same.

The verb be can mean pray in some contexts, but not here.

In this sentence, bad mig bläddra clearly means asked me to leaf through / turn the pages. The context with bibliotekarien and boken makes ask/request the natural meaning.

More or less, yes:

• Bibliotekarien = the librarian
• bad = asked
• mig = me
• bläddra = leaf through / turn pages
• försiktigt = carefully
• eftersom = because
• boken = the book
• var = was
• gammal = old

A fairly close English version is:

The librarian asked me to turn the pages carefully, because the book was old.

Or more naturally:

The librarian asked me to handle the book carefully, because it was old.

Yes. It is very typical and natural.

It has:

1. a main clause:
   Bibliotekarien bad mig bläddra försiktigt

2. a subordinate clause giving the reason:
   eftersom boken var gammal

This is a very common Swedish pattern:

• main statement first
• explanation introduced by eftersom

So it is a good example of everyday Swedish sentence structure.