Det är omöjligt att undvika allt matsvinn.

Because Swedish often uses det är in the same way English uses it is in general statements.

Here, det does not refer to a specific thing. It is a dummy subject, just like it in English sentences such as:

• It is difficult to understand
• It is impossible to avoid all food waste

So Det är omöjligt... is a very standard Swedish pattern.

Because the adjective is in the neuter form.

The base forms work like this:

• en omöjlig uppgift = an impossible task
• ett omöjligt mål = an impossible goal

After det är, Swedish normally uses the form that matches ett words, so you get omöjligt.

This is very common:

• Det är svårt
• Det är viktigt
• Det är möjligt
• Det är omöjligt

Here att is the infinitive marker, like English to.

So:

• att undvika = to avoid

In this sentence, att undvika allt matsvinn is the idea that follows omöjligt:

• Det är omöjligt att... = It is impossible to...

This pattern is extremely common in Swedish.

Because after the infinitive marker att, Swedish uses the infinitive form of the verb.

So:

• undvika = infinitive, to avoid
• undviker = present tense, avoid / avoids
• undvek = past tense, avoided
• undvikit = supine, used in perfect tenses

Since the sentence has att, the infinitive undvika is required.

Because matsvinn is a neuter noun and is being used as an uncountable mass noun.

The forms of all are:

• all for common gender singular nouns
• allt for neuter singular nouns and mass nouns
• alla for plural nouns

Compare:

• all mat = all food
• allt vatten = all water
• allt matsvinn = all food waste
• alla äpplen = all apples

So allt is the correct form here.

Because matsvinn is being used in a general, uncountable sense.

In Swedish, mass nouns often appear without an article when you mean the thing in general:

• vatten = water
• arbete = work
• matsvinn = food waste

So allt matsvinn means all food waste in general, not one specific portion of it.

It is a compound noun, which is very common in Swedish.

It is made up of:

• mat = food
• svinn = waste, loss, shrinkage

So matsvinn literally means something like food waste or food loss.

Swedish forms many nouns this way, by combining smaller words into one larger word.

Not exactly.

• matsvinn usually means food that could have been eaten but was wasted
• matavfall is broader and can include food scraps that are not meant to be eaten, such as peels or bones

So matsvinn often focuses on avoidable waste, which makes it a good choice in this sentence.

The structure is:

• Det = subject
• är = verb
• omöjligt = subject complement
• att undvika allt matsvinn = infinitive phrase

So the sentence is built like this:

Det är + adjective + att + infinitive

This is a very common Swedish pattern, for example:

• Det är lätt att förstå
• Det är svårt att veta
• Det är viktigt att komma i tid

In normal full Swedish sentences, no. Swedish usually needs the dummy subject det here.

So standard Swedish is:

• Det är omöjligt att undvika allt matsvinn

Leaving out det would sound incomplete in ordinary prose or speech.