Jag rekommenderar leden längs kusten.

Rekommenderar is the present tense of rekommendera = to recommend.

So:

• jag rekommenderar = I recommend
• du rekommenderar = you recommend
• vi rekommenderar = we recommend

A useful thing to know: Swedish verbs do not change form depending on the person, the way English does with I recommend / he recommends.

In Swedish, the is often added to the end of the noun instead of being a separate word.

So here:

• led = trail / route
• leden = the trail

and

• kust = coast
• kusten = the coast

So leden längs kusten literally contains the trail along the coast, even though there is no separate word like English the.

Because leden means the trail, while en led means a trail.

So the difference is:

• Jag rekommenderar leden längs kusten. = I recommend the trail along the coast.
• Jag rekommenderar en led längs kusten. = I recommend a trail along the coast.

The version with leden sounds like the speaker has a specific trail in mind.

Längs is a preposition meaning along.

Examples:

• längs kusten = along the coast
• längs vägen = along the road
• längs floden = along the river

So in this sentence, längs kusten tells you where the trail runs: along the coast.

No, längs does not automatically require the definite form.

You can have either, depending on the meaning:

• längs kusten = along the coast
• längs en kust = along a coast

In this sentence, kusten is definite because the speaker means a specific or understood coast, not just any coast.

Led can mean things like trail, path, route, or track, depending on context.

In this sentence, it most naturally means a trail or route, especially something like a walking or hiking trail along the coast.

So while trail is probably the best everyday translation here, route may also fit in some contexts.

The sentence follows a very normal Swedish main-clause pattern:

• Jag = subject
• rekommenderar = verb
• leden = object
• längs kusten = prepositional phrase

So the structure is basically:

Subject + Verb + Object + Extra information

Very literally: I recommend the trail along the coast.

This is straightforward Swedish word order.

In this sentence, längs kusten most naturally describes leden.

So the meaning is:

• the trail along the coast

not

• I recommend it along the coast

In other words, the speaker is recommending which trail: the one that goes along the coast.

Yes, you can. It is grammatical, but the meaning changes.

• Jag rekommenderar leden längs kusten = I recommend the trail along the coast
  → a specific trail

• Jag rekommenderar en led längs kusten = I recommend a trail along the coast
  → one trail among possible others

So the choice between en led and leden depends on whether you mean a trail or the trail.

Yes. Both are common gender nouns, so they take en in the indefinite form:

• en led
• en kust

Their definite singular forms are:

• leden
• kusten

This is why both definite forms end in -en.