Après le dîner, nous allons faire un tour au bord de la mer.

Both forms exist, but they’re not used in exactly the same way.

• Après le dîner = after the (specific) dinner.
  You’re talking about tonight’s dinner, a particular meal that is known in context.

• Après dîner (no article) = more general, like after dinner (in general) or in a habitual sense:

  • Après dîner, je lis un peu. – After dinner, I read a bit (as a habit).

In your sentence, it’s about a specific event in time (this evening), so Après le dîner is the most natural choice.

Yes. Nous allons faire is the near future (futur proche) in French:

• Structure: aller (present) + infinitive
  
  • nous allons (we go / we are going) + faire (to do)
    → nous allons faire = we are going to do / we’re going to make.

It works very much like English “to be going to”:

• Nous allons faire un tour… = We’re going to take a walk / go for a stroll…

It often suggests something planned, fairly soon in time.

Both are future, but with a nuance:

• Nous allons faire un tour

  • Near future (futur proche).
  • Feels more immediate, planned, conversational.
  • Very common in spoken French.

• Nous ferons un tour

  • Simple future (futur simple).
  • More neutral, slightly more formal or distant.
  • Common in writing, or for less immediate plans.

In everyday spoken French, people use nous allons faire more often than nous ferons in this kind of sentence.

Literally, faire un tour means “to do/make a turn”, but idiomatically it means:

• to go for a walk / stroll
• to go for a ride / spin (in a car, on a bike, etc.)
• to look around (e.g. in town, in a museum)

In your sentence, faire un tour au bord de la mer most naturally means go for a walk / stroll by the sea.

Other possible expressions for a similar idea:

• faire une promenade – to go for a walk (a bit more formal/literary)
• se promener – to take a walk, to stroll

But faire un tour is very common and sounds casual and natural.

French has two different words that are spelled the same but have different genders and meanings:

• un tour (masculine)

  • a turn, a trip around, a walk/ride
  • used in faire un tour (go for a walk/ride).

• une tour (feminine)

  • a tower (building)
  • e.g. la tour Eiffel – the Eiffel Tower.

Here we need the masculine noun un tour, because we are talking about a walk/outing, not a tower.

They don’t mean quite the same thing:

• au bord de la mer

  • literally: at the edge/bank/shore of the sea
  • focuses on being right by the water, on the shore / seafront.

• à la mer

  • literally: to the sea / at the sea
  • often means “to the seaside” or being in a seaside location more generally, not necessarily right on the water’s edge.
  • e.g. Nous partons à la mer. – We’re going to the seaside (for a trip/holiday).

Your sentence wants to emphasize a walk along the shore, so au bord de la mer is the natural choice.

The phrase breaks down like this:

• à + le bord → au bord (contraction)

  • bord = edge, side, shore (masculine noun).
  • au is just à le fused together.

• de la mer

  • de + la mer (no contraction, because mer is feminine).
  • mer = sea.

So:

• au bord de la mer = at the edge/shore of the sea.
  It’s a fixed pattern: au bord de + [what you’re on the edge of]
  e.g. au bord du lac (lake), au bord de la route (road).

Yes, but it changes the image slightly:

• au bord de la mer

  • more general: along the seafront / shoreline; could be on a promenade, a path, or even cliffs.

• à la plage

  • specifically to the beach (the sandy/pebbly area where people swim, sunbathe, etc.).

Both are correct; you just emphasize a different place:

• If the idea is a general coastal walk → au bord de la mer.
• If the idea is going specifically to the beach area → à la plage.

Yes. Both of these are correct:

• Après le dîner, nous allons faire un tour au bord de la mer.
• Nous allons faire un tour au bord de la mer après le dîner.

Putting Après le dîner at the beginning slightly emphasizes when it will happen, but the meaning is the same. French word order is flexible for time expressions like this.

In standard French, you normally need the article with mer:

• la mer – the sea
• au bord de la mer – by the sea

Au bord de mer without the article is not standard in this context and sounds wrong to native speakers.

There is, however, a different fixed expression en bord de mer (no article), which means “seaside / on the seafront”, often used in ads, descriptions, etc.:

• Un hôtel en bord de mer. – A seaside hotel.

But in your sentence, the normal structure is au bord de la mer.

Yes, there are some common liaisons:

• nous allons → pronounced like nou-z-allons

  • The s of nous links to allons.

• allons faire → often you’ll hear a very light link: allon(f) faire, but it’s weaker and less obligatory than nous allons.

• faire un → often sounds like fèr-un; some speakers make a light liaison (fèr-un), but you shouldn’t pronounce an extra consonant that isn’t there.

So a natural flow is roughly:

• Après le dîner, nou-z-al-lon fèr-un tour au bord de la mer.