Om det finns ett bra erbjudande, vill jag behålla medlemskapet.

Om means if here. It introduces a condition:

• Om det finns ett bra erbjudande = If there is a good offer

This is a very common way to build conditional sentences in Swedish, just like in English:

• Om jag har tid, kommer jag. = If I have time, I’ll come.

So in your sentence, the first part sets the condition, and the second part gives the result.

Det finns means there is or there are.

Even though det literally often means it, in this expression it is part of the standard Swedish way to say that something exists.

So:

• det finns ett bra erbjudande = there is a good offer

You usually learn det finns as a fixed expression.

Examples:

• Det finns en park här. = There is a park here.
• Det finns många problem. = There are many problems.

So det here does not mean a specific it in the same way it often does in English.

Because erbjudande is an ett-word in Swedish.

Swedish nouns have two grammatical genders in modern standard Swedish:

• en-words
• ett-words

Since erbjudande takes ett, you say:

• ett erbjudande = an offer

With the adjective:

• ett bra erbjudande = a good offer

So the article has to match the noun’s gender.

Many Swedish adjectives change depending on the noun, but bra is irregular in the sense that it usually stays bra.

Compare:

• en stor bil = a big car
• ett stort hus = a big house

But with bra:

• en bra bil
• ett bra hus
• bra bilar

So in ett bra erbjudande, bra stays the same.

This is because of Swedish word order, especially the V2 rule.

The sentence begins with a subordinate clause:

• Om det finns ett bra erbjudande

After that comes the main clause. In Swedish main clauses, the finite verb usually comes in second position. Since the conditional clause takes the first position, the verb comes before the subject in the main clause:

• Om det finns ett bra erbjudande, vill jag behålla medlemskapet.

Not:

• Om det finns ett bra erbjudande, jag vill behålla medlemskapet. ❌

This inversion is very common in Swedish:

• Idag går jag till jobbet.
• Om du kommer, blir jag glad.

Because it comes after vill.

In Swedish, modal verbs such as vill (want to), kan (can), måste (must) are followed by the infinitive form of the next verb.

So:

• vill behålla = want to keep
• kan komma = can come
• måste gå = must go

That is why you get:

• jag vill behålla medlemskapet

and not a conjugated form after vill.

Medlemskap means membership.

The ending -et is the Swedish definite article attached to the noun, so:

• ett medlemskap = a membership
• medlemskapet = the membership

Swedish often puts the at the end of the noun instead of using a separate word like English does.

So:

• bok = book
• boken = the book

And here:

• medlemskapet = the membership

In Swedish, it is often natural to use the definite form when talking about a specific thing already understood from the context.

Here, medlemskapet suggests a specific membership — for example, my current membership, the membership we’ve been talking about, or the membership with that company.

English sometimes uses a possessive or leaves things more flexible, but Swedish often uses the definite form in cases like this.

A learner might expect something like ett medlemskap, but that would sound more like a membership in a general sense, not the particular one being discussed.

The comma is acceptable, but in modern Swedish it is often omitted.

So both of these are possible:

• Om det finns ett bra erbjudande, vill jag behålla medlemskapet.
• Om det finns ett bra erbjudande vill jag behålla medlemskapet.

The meaning is the same.

Writers vary in how much they use commas with introductory subordinate clauses. You will often see no comma in everyday Swedish.

Yes, but the meaning shifts slightly.

• Om det finns ett bra erbjudande = If there is a good offer
  This focuses on whether such an offer exists.

• Om det är ett bra erbjudande = If it is a good offer
  This sounds more like you are evaluating an offer that already exists.

So finns is the better choice when you mean if such an offer is available / exists.

It has two parts:

1. Subordinate clause: Om det finns ett bra erbjudande
2. Main clause: vill jag behålla medlemskapet

So the pattern is:

• Om + clause, verb + subject + infinitive ...

More literally:

• If there is a good offer, want I keep the membership

That literal word order sounds wrong in English, but it is normal Swedish because of the verb-second rule in the main clause.

Yes, absolutely.

This version is also natural:

• Jag vill behålla medlemskapet om det finns ett bra erbjudande.

The meaning stays basically the same.

The main difference is emphasis:

• Om det finns ett bra erbjudande, vill jag behålla medlemskapet.
  This emphasizes the condition first.

• Jag vill behålla medlemskapet om det finns ett bra erbjudande.
  This starts with what you want, then adds the condition.

When the main clause comes first, normal word order stays:

• Jag vill ...
  not
• Vill jag ...

In speech, Swedish speakers would often group it like this:

• Om det finns ett bra erbjudande | vill jag behålla medlemskapet.

The first part sets up the condition, and the second part gives the result.

You may also hear a slight pause after the first clause, especially if the speaker wants to be clear or emphasize the condition. That pause is one reason some people choose to write a comma there.