Сегодня мы едем на ферму за город.

Russian distinguishes between going by transport and going on foot.

• ехать / едем = to go by car, bus, train, etc.
• идти / идём = to go on foot

So мы едем suggests that the speakers are traveling to the farm by some vehicle. If they were walking, you would normally say Сегодня мы идём на ферму за город.

Formally, едем is present tense. However, in Russian, the present tense of an imperfective verb is often used for a planned near-future action, especially when there is a time word like сегодня.

So here Сегодня мы едем... means something like:

• we’re going today
• we are going today
• today we’re heading out

This is very natural in Russian, just like English can say We’re going today.

This is mainly a matter of Russian idiomatic usage. Some places take в, while others take на.

A farm is normally treated as a destination that takes на:

• на ферму
• на рынок
• на завод
• на стадион

So ехать на ферму is the normal way to say go to a farm.

Using в ферму would sound unnatural in standard Russian.

Ферму is accusative singular.

The dictionary form is ферма. Since the sentence shows motion toward a destination with на, Russian uses the accusative case:

• ферма → nominative
• на ферму → accusative, because it means movement to the farm

Compare:

• Мы едем на ферму = we are going to the farm
• Мы на ферме = we are at the farm

In the second example, на ферме is prepositional, because it describes location rather than movement.

За город is a very common Russian expression meaning out of town, outside the city, or into the countryside.

Literally, за can mean beyond or behind, so за город is something like beyond the city.

In this sentence, it tells you where the farm is or what direction the speakers are going: not in the city, but outside it.

This is a case difference tied to movement vs. location.

• за город = motion to a place beyond the city
• за городом = location outside the city

So:

• Сегодня мы едем за город = Today we’re going out of town
• Ферма находится за городом = The farm is located outside the city

In your sentence, there is movement, so за takes the accusative: город.

Yes, very often.

Russian frequently leaves out subject pronouns because the verb ending already shows who is doing the action. Едем already means we are going.

So both are possible:

• Сегодня мы едем на ферму за город
• Сегодня едем на ферму за город

Including мы can make the sentence a little clearer, more explicit, or slightly more emphatic. Omitting it is also natural if the context is clear.

Yes, the word order can change. Russian word order is flexible.

Placing сегодня first gives the time frame right away:

• Сегодня мы едем на ферму за город

Other natural orders are possible too:

• Мы сегодня едем на ферму за город
• На ферму за город мы едем сегодня

The basic meaning stays the same, but the emphasis changes. The version in your sentence is very natural and neutral if the speaker wants to foreground today.

Russian has no articles, so there is no direct equivalent of a or the in the sentence.

That means на ферму could be understood as:

• to a farm
• to the farm

The exact meaning depends on context.

If Russian wants to be more specific, it can use other words, such as:

• на эту ферму = to this farm
• на нашу ферму = to our farm

But very often context is enough.

Both can refer to the future, but the nuance is different.

• едем focuses on the trip as a current plan or arranged movement
• поедем is a perfective future form, often meaning we will go, we will set off

Compare:

• Сегодня мы едем на ферму = Today we’re going to the farm
• Сегодня мы поедем на ферму = Today we will go to the farm / will set off for the farm

In many situations both are possible, but едем often sounds more like an already settled plan, similar to English we’re going.

In practice, it can feel like it does both.

The phrase на ферму за город naturally suggests to a farm outside the city. So за город helps describe where the farm is.

At the same time, because it follows a verb of motion, it also contributes to the idea of direction: the speakers are going out of town.

Russian often allows this kind of compact phrasing, where one short phrase fits naturally into the whole destination idea without needing extra words like которая находится.