Min väska är lätt, men min resväska är tung.

Because väska and resväska are en-words (common gender nouns).

In Swedish possessives change like this:

• min
  • singular en-word
• mitt
  • singular ett-word
• mina
  • plural

So:

• min väska
• min resväska

Compare:

• mitt hus = my house
• mina väskor = my bags

A useful clue: when you see min, the noun is usually a singular en-word.

Because Swedish does not use an article together with a possessive in this kind of phrase.

So you say:

• min väska
• min resväska

not:

• min en väska
• min en resväska

This works much like English:

• my bag, not my a bag

The same idea also means you do not use the definite ending here either. Standard Swedish says min väska, not min väskan.

Väska is a general word for a bag.

Resväska is more specific: it means a travel bag / suitcase.

So resväska is basically a type of väska.

This is very common in Swedish: a general noun can become more specific by adding another word in front of it.

Because Swedish usually writes compound nouns as one word.

Resväska is made from:

• resa = trip, travel
• väska = bag

Together they form resväska.

This is an important difference from English, where similar expressions are often written as two words. Swedish prefers compounds such as:

• sommarhus = summer house
• sjukhus = hospital
• handväska = handbag

So writing res väska would be wrong.

Because each noun phrase needs its own possessive if you want both items to be clearly understood as mine.

• Min väska är lätt, men min resväska är tung.

This clearly tells us:

• my bag is light
• my suitcase is heavy

If you remove the second min, the meaning changes or becomes less natural. For example:

• Min väska är lätt, men resväskan är tung

That means something more like:

• my bag is light, but the suitcase is heavy

So repeating min is the normal way to show that both nouns belong to the same person.

Är is the present tense of vara, the verb to be.

So here it works just like is in English:

• väskan är lätt = the bag is light
• resväskan är tung = the suitcase is heavy

It connects the subject to an adjective.

You need är in both parts because the sentence contains two full clauses:

• Min väska är lätt
• men min resväska är tung

Because Swedish adjectives agree with the noun, even after är.

Here both nouns are:

• singular
• en-words

So the adjective takes the common singular form:

• en väska är tung
• min väska är lätt

If the noun were an ett-word, many adjectives would change:

• ett bord är tungt

If the noun were plural, the adjective would usually take -a:

• väskorna är tunga

A small trap: lätt already looks like a form with -t, but that is simply the normal form here. So even though tung changes to tungt with an ett-word, lätt stays lätt in both common singular and neuter singular.

Men means but.

It joins two contrasting main clauses:

• Min väska är lätt
• men min resväska är tung

The comma is natural here because two full clauses are being joined.

After men, Swedish keeps normal main-clause word order:

• men min resväska är tung

So there is no special change caused by men itself.

Yes. Lätt can mean both:

• light in weight
• easy

Context tells you which meaning is intended.

Examples:

• Väskan är lätt = the bag is light
• Det är lätt = it is easy

In this sentence, because we are talking about a bag and a suitcase, light in weight is the intended meaning.

A good beginner approximation is that ä often sounds somewhat like the vowel in bed.

So:

• väska starts with a sound a bit like ves-
• lätt has that same kind of vowel
• är also contains ä, though the whole word has no exact English equivalent

A few helpful pronunciation notes:

• väska has stress on the first syllable
• resväska also has main stress on the first part of the compound
• tung ends with ng like in sing
• the u in tung does not have an exact English match, so it takes practice

If you want to sound natural, the biggest things to focus on here are:

• the ä sound
• the stress on VÄS-ka
• the stress on RES-väska