Grammatiken känns svår i dag, men i morgon förstår jag den kanske bättre.

Because Swedish often uses the definite form for a specific topic or system that is already in focus.

Here, grammatiken means the grammar—in other words, the grammar of the language being studied. In English, we often just say grammar with no article, but Swedish more naturally says grammatiken in this kind of context.

Compare:

• Jag gillar grammatik. = I like grammar.
• Grammatiken är svår. = The grammar is difficult.

Känns comes from kännas, which means to feel or to seem.

So Grammatiken känns svår is literally something like:

• The grammar feels difficult
• or The grammar seems hard

It is more subjective than är.

Compare:

• Grammatiken är svår. = The grammar is difficult.
• Grammatiken känns svår. = The grammar feels difficult / seems difficult.

So the sentence is expressing the speaker’s impression, not making a completely objective statement.

Because grammatiken is a common gender noun (an en word), not a neuter noun (an ett word).

In Swedish, predicative adjectives agree with the noun:

• en-word, singular: svår
• ett-word, singular: svårt
• plural: svåra

So:

• en grammatik → grammatiken känns svår
• ett problem → problemet känns svårt
• reglerna → reglerna känns svåra

Both the two-word and one-word spellings are accepted:

• i dag / idag
• i morgon / imorgon

The two-word versions can feel a little more traditional or careful in writing, while the one-word versions are very common in modern everyday Swedish.

So this sentence could also be written:

Grammatiken känns svår idag, men imorgon förstår jag den kanske bättre.

Because Swedish follows the V2 rule in main clauses: the finite verb must come in the second position.

In this sentence, i morgon is placed first. That means the finite verb förstår has to come next, and the subject jag comes after it.

So:

• I morgon förstår jag den kanske bättre. ✅
• I morgon jag förstår den kanske bättre. ❌

If the sentence started with the subject instead, then the order would be:

• Jag förstår den kanske bättre i morgon.

Both are possible, but the emphasis is slightly different.

Because Swedish very often uses the present tense to talk about the future when a time expression makes the future clear.

Here, i morgon already tells us that the action is in the future, so förstår is enough.

This is very normal Swedish:

• I morgon jobbar jag hemma. = Tomorrow I’m working from home.
• Nästa vecka åker vi till Stockholm. = Next week we’re going to Stockholm.

You do not always need a special future form like ska.

Den means it, and it refers back to grammatiken.

Since grammatik is an en word, the pronoun is den:

• en grammatik → den

If the noun were an ett word, the pronoun would be det instead.

Compare:

• Jag förstår grammatiken. Jag förstår den.
• Jag förstår ordet. Jag förstår det.

So den is just the correct object pronoun for grammatiken.

In Swedish, short unstressed object pronouns like den, det, honom, henne, dem often come before sentence adverbs such as inte, nog, kanske.

So förstår jag den kanske bättre is natural Swedish word order.

A useful pattern is:

• finite verb
• subject
• short object pronoun
• sentence adverb

So here:

• förstår = finite verb
• jag = subject
• den = object pronoun
• kanske = sentence adverb

You may also hear other word orders with kanske, especially if the speaker wants different emphasis, for example:

• I morgon kanske jag förstår den bättre.

That is also correct, but it is structured a little differently.

Bättre is the comparative form of bra and means better.

Here it functions adverbially with förstår:

• förstår bättre = understand better

Swedish uses bättre for both adjective and adverb uses, so you do not need a separate form like English better.

Compare:

• Jag mår bättre. = I feel better.
• Jag förstår den bättre. = I understand it better.
• en bättre bok = a better book

Yes. Kanske is fairly mobile, and moving it changes the emphasis a bit.

For example:

• I morgon förstår jag den kanske bättre.
• I morgon kanske jag förstår den bättre.

Both are grammatical.

A rough difference is:

• I morgon kanske jag förstår den bättre puts maybe/perhaps earlier and makes the uncertainty stand out sooner.
• I morgon förstår jag den kanske bättre first presents tomorrow I understand it..., then adds perhaps, which gives a slightly different rhythm.

So the original sentence is correct, but it is not the only possible word order.