Hvis vi taler roligt, bliver vi enige om planen.

Because Danish uses V2 word order in main clauses: the finite verb normally comes in second position.

Here, the sentence starts with the subordinate clause Hvis vi taler roligt. After that whole clause, the main clause begins, and its finite verb bliver must come first:

• Hvis vi taler roligt, bliver vi enige om planen.

So even though vi is the subject, bliver comes before it because the sentence has already started with something else.

Compare:

• Vi bliver enige om planen.
• I morgen bliver vi enige om planen.
• Hvis vi taler roligt, bliver vi enige om planen.

In all of these, the finite verb stays in second position in the main clause.

Danish often uses the present tense for general truths, habits, and future situations, especially in if-clauses.

So:

• Hvis vi taler roligt... = If we speak calmly...

This is normal Danish. You do not usually use vil inside this kind of conditional clause.

English also does something similar:

• If we speak calmly, ... not
• If we will speak calmly, ...

So the Danish structure is very natural here.

Roligt is the adverb form of rolig.

• rolig = calm
• roligt = calmly / in a calm way

In Danish, many adjectives add -t when they are used as adverbs with a verb.

Examples:

• Han taler langsomt. = He speaks slowly.
• De arbejder hurtigt. = They work quickly.
• Vi taler roligt. = We speak calmly.

So roligt describes how we speak.

At blive enig means to become agreed or, more naturally in English, to come to an agreement.

So:

• vi bliver enige = we come to an agreement
• de blev enige = they reached an agreement

This is a very common Danish expression. Danish often uses blive + adjective to express a change of state:

• blive træt = become tired
• blive glad = become happy
• blive enig = come to agree

In your sentence, bliver vi enige om planen means something like we will manage to agree about the plan.

Because the subject is vi = we, which is plural.

The adjective changes like this:

• jeg er enig = I agree
• han er enig = he agrees
• vi er enige = we agree
• de er enige = they agree

So after plural subjects, Danish uses enige.

That same pattern appears after blive as well:

• jeg bliver enig
• vi bliver enige

Because Danish says enig om noget = agreed about/on something.

So:

• Vi er enige om planen. = We agree on/about the plan.
• De blev enige om prisen. = They agreed on the price.

The preposition om belongs naturally with enig/enige when you say what the agreement is about.

This is something you usually just learn as a fixed pattern:

• enig om noget
• uenig om noget = disagree about something

Yes:

• Vi bliver enige om planen, hvis vi taler roligt.

This means the same thing.

The difference is mostly about focus and word order:

• Hvis vi taler roligt, bliver vi enige om planen.
  The condition comes first.
• Vi bliver enige om planen, hvis vi taler roligt.
  The result comes first.

Notice that when the main clause comes first, the word order is the normal:

• Vi bliver ...

But when the sentence starts with the hvis-clause, the main clause shows inversion:

• ... bliver vi ...

Because Hvis vi taler roligt is a subordinate clause, and it is separated from the main clause by a comma.

So the structure is:

• Hvis vi taler roligt = subordinate clause
• bliver vi enige om planen = main clause

In written Danish, this comma helps show the boundary between the two parts.

Usually, yes. In sentences like this, hvis means if.

Examples:

• Hvis det regner, bliver vi hjemme. = If it rains, we stay home.
• Hvis du vil, kan jeg hjælpe. = If you want, I can help.

But learners should also know that Danish sometimes uses når where English might use if/when, depending on whether something is seen as general or expected. In your sentence, hvis is the natural choice for a condition: if we speak calmly.

Yes. In this sentence, taler could be translated as either speak or talk, depending on what sounds best in English.

• If we speak calmly...
• If we talk calmly...

Both are fine. Danish tale often covers both ideas.

It can be understood as either, depending on context.

It may mean:

• a general truth: whenever we speak calmly, we end up agreeing on the plan
• a future/potential situation: if we speak calmly now, we will agree on the plan

Danish present tense often leaves that open, and context tells you which meaning is intended.

You would normally use past forms to make it more hypothetical:

• Hvis vi talte roligt, blev vi enige om planen.

However, Danish often uses other wording too, depending on how clearly unreal or hypothetical you want it to sound.

The original sentence:

• Hvis vi taler roligt, bliver vi enige om planen.

sounds natural for a real possibility or likely result.

So for learners, the important point is:

• present + present is very common in real conditions
• more hypothetical meanings may use past forms or other phrasing

In careful pronunciation, bliver is something like BLI-ver, but in natural spoken Danish it is often reduced.

Many learners hear something closer to:

• bli’r

That apostrophe-style spelling is sometimes used informally to show the shortened pronunciation, though the normal written form is still bliver.

So if native speakers seem to skip part of the word, that is normal.