Genbruget bliver lettere, når vi sorterer glas og metal for sig.

Genbruget is the definite singular form of genbrug, meaning the recycling.

In Danish, many nouns add -et or -en to mean the ...:

• et hus → huset = the house
• genbrug → genbruget = the recycling

Here, Danish is talking about recycling in a general but specific sense: recycling as a system/process becomes easier.

Bliver lettere means becomes easier.

• bliver = becomes / gets
• lettere = easier

So this is about a change of state:

• not just that recycling is easy
• but that it becomes easier

That is why bliver is used instead of er.

Because lettere is the comparative form of let.

• let = easy / light
• lettere = easier
• lettest = easiest

In this sentence, the idea is that recycling is easier than before or easier because of sorting, so Danish uses the comparative.

Because når vi sorterer glas og metal for sig is a subordinate clause.

Danish normally uses a comma before subordinate clauses introduced by words like:

• når = when
• hvis = if
• fordi = because
• at = that

So the comma helps separate the main clause from the subordinate clause:

• Genbruget bliver lettere = main clause
• når vi sorterer glas og metal for sig = subordinate clause

Here når means when.

So the sentence means that recycling becomes easier when we sort glass and metal separately.

In many cases, når is used for:

• something that happens when something else happens
• repeated or general situations

That fits this sentence well: whenever we sort glass and metal separately, recycling becomes easier.

Because after når, Danish uses subordinate clause word order.

In a normal main clause, Danish often has the verb in second position:

• Vi sorterer glas og metal.

But in a subordinate clause introduced by når, the subject usually comes before the verb:

• når vi sorterer glas og metal

So:

• Vi sorterer ... = main clause
• når vi sorterer ... = subordinate clause

That is normal Danish grammar.

Because Danish often leaves out articles when talking about materials or things in a general sense.

Here glas og metal means glass and metal as categories of waste/material, not:

• a glass
• the glass
• a metal

So this is similar to English, where we also often say:

• We recycle glass and metal rather than
• We recycle the glass and the metal

For sig means separately, each on its own, or apart.

So:

• sorterer glas og metal for sig = sort glass and metal separately

This expression is very common in Danish. It often suggests that things are kept apart from each other.

Examples:

• Hold dem for sig. = Keep them separate.
• Børnene leger hver for sig. = The children play separately / each on their own.

In this sentence, it means that glass and metal should not be mixed together.

Because Danish often uses the present tense for general truths, habits, and instructions about how things work.

So:

• Genbruget bliver lettere = Recycling becomes easier
• når vi sorterer ... = when we sort ...

This does not have to mean only right now. It can mean something generally true: Recycling becomes easier whenever we sort glass and metal separately.

English does the same thing:

• Water boils at 100°C
• Life gets easier when we plan ahead

Yes, in some contexts you could use words like:

• separat = separate / separately
• hver for sig = each separately

But for sig is very natural here.

For example:

• sorterer glas og metal separat is understandable
• sorterer glas og metal for sig sounds very idiomatic and natural

A small nuance:

• for sig often sounds like kept apart
• separat can sound a bit more formal or technical

It can cover both ideas depending on context, which can be confusing for English speakers.

Genbrug literally suggests use again, so it can relate to:

• reuse
• recycling
• the general system of handling reusable/recyclable materials

In this sentence, because it talks about sorting glass and metal, genbruget is best understood as recycling.

If Danish wants to be more specifically technical about recycling, it may also use:

• genanvendelse = recycling / reutilization

But in everyday Danish, genbrug is extremely common.

In Danish, material words often stay in a basic form when referring to the material in general.

So:

• glas = glass
• metal = metal

They are not talking about individual objects like:

• bottles
• jars
• cans

They are talking about the material categories. English often does the same:

• We sort paper, glass, and metal rather than
• We sort papers, glasses, and metals

Yes. If the subordinate clause comes first, then the main clause follows normal Danish verb-second order.

So you could say:

• Når vi sorterer glas og metal for sig, bliver genbruget lettere.

Notice that after the opening clause, Danish says:

• bliver genbruget not
• genbruget bliver

That is because the verb takes second position in the main clause.

So:

• Genbruget bliver lettere, når vi sorterer ...
• Når vi sorterer ..., bliver genbruget lettere.

Both are correct.