Learn Hardcore German: Ich bin mit meinem Ergebnis unzufrieden, aber dafür kenne ich jetzt meine Schwächen besser. - I am dissatisfied with my result, but because of that I now know my weaknesses better.

mit always takes the dative case, which is why we get meinem Ergebnis (dative neuter), not mein Ergebnis.
So the pattern is:
unzufrieden mit + dative
e.g. Ich bin mit dem Ergebnis unzufrieden.

You can say unzufrieden über in some contexts, but that usually means upset/annoyed about something that happened, rather than dissatisfied with a result or object. For a test result, performance, grade, etc., mit is the normal choice.

Why is it meinem Ergebnis and not mein Ergebnis or meinen Ergebnis?

This is a case ending issue:

The noun Ergebnis is neuter: das Ergebnis.
The preposition mit always requires the dative case.
Neuter dative with a possessive like mein- takes the ending -em:
- nominative: mein Ergebnis
- accusative: mein Ergebnis
- dative: meinem Ergebnis
- genitive: meines Ergebnisses

So after mit, you must say mit meinem Ergebnis.

What exactly does dafür mean in this sentence?

Literally, dafür is da (there/that) + für (for), so: for that / for it.

In this sentence, though, it is used in a more idiomatic, contrastive way. The whole aber dafür here can be understood as:

but in return
but on the other hand
but at least
but in compensation for that

So it contrasts the first part (being dissatisfied) with a positive side effect (knowing your weaknesses better).

Why do we say aber dafür instead of just aber or just dafür?

Each has a slightly different nuance:

aber = but, a simple contrast.
dafür alone would be odd at the start of the clause here; it usually needs a clear, explicit reference and some context, and it wouldn’t by itself signal the “compensation” idea as clearly.

aber dafür together:

introduces a contrasting positive aspect that partly compensates for the negative one.
feels similar to “but on the plus side…” or “but in return…” in English.

You could say:

Ich bin mit meinem Ergebnis unzufrieden, aber ich kenne jetzt meine Schwächen besser.
→ Neutral contrast: “but I know my weaknesses better now.”

With aber dafür, it sounds more like:
“I’m unhappy with my result, but at least I now know my weaknesses better.”

Why is the word order … aber dafür kenne ich jetzt meine Schwächen besser and not … aber dafür ich kenne jetzt …?

German main clauses follow the verb-second (V2) rule:

The finite verb (here: kenne) must be in second position in the clause.
Second position means: after the first constituent, which can be one word or a whole phrase.

In this clause:

First constituent: aber dafür (treated together as the “first slot”)
Second position: kenne (the finite verb)
Then: ich jetzt meine Schwächen besser

You cannot put ich before kenne here, because that would move the verb out of second position:

❌ aber dafür ich kenne jetzt … → verb is in third position → wrong.

Correct alternatives (each keeps verb in 2nd place):

aber ich kenne jetzt meine Schwächen besser (first: ich)
aber jetzt kenne ich meine Schwächen besser (first: jetzt)
aber dafür kenne ich jetzt meine Schwächen besser (first: dafür)

Could we say weiß instead of kenne here?

No, weiß would not be idiomatic in this sentence.

Difference:

kennen = to be familiar with, to know (a person/thing/area).
wissen (ich weiß) = to know a fact, information, a piece of knowledge.

We use:

jemanden/etwas kennen → know a person/thing/area/weaknesses
etwas wissen → know that… / know what… / know why… etc.

So here:

meine Schwächen kennen = be familiar with my weaknesses → correct
meine Schwächen wissen = wrong; you don’t “wissen” weaknesses as objects.

So dafür kenne ich jetzt meine Schwächen besser is the natural choice.

What does Schwächen mean here, and how is it different from Fehler?

Schwäche (plural Schwächen) = weakness(es), areas where you’re not strong or not very good.
Fehler (plural is the same form) = mistake(s), error(s).

In this context:

meine Schwächen = my general weak points (e.g. grammar areas, types of tasks, skills).
meine Fehler would mean the specific mistakes you made.

The sentence emphasizes that the speaker now has a better understanding of their general weaknesses, not just individual errors.

What is besser modifying, and why is it at the end?

besser is the comparative of “gut”: better.

In this sentence, besser modifies the verb “kennen”:

ich kenne meine Schwächen besser = I know my weaknesses better (than before).

About its position:

In German, adverbs like besser often come towards the end of the clause, especially after the main objects.
So the order meine Schwächen besser is completely natural:
- subject: ich
- verb: kenne
- object: meine Schwächen
- adverb: besser

Can we leave out jetzt? What does jetzt add?

Yes, grammatically you can leave it out:

… aber dafür kenne ich meine Schwächen besser.

jetzt means now, and it adds a time contrast:

Before: I didn’t know my weaknesses as well.
Now (after this experience/result): I know them better.

So jetzt emphasizes the change over time caused by the situation (e.g. taking a test, getting a result).

Word order variants, all correct but with slightly different emphasis:

Ich kenne jetzt meine Schwächen besser.
Jetzt kenne ich meine Schwächen besser.
Ich kenne meine Schwächen jetzt besser.

They all mean essentially the same; jetzt can move around fairly freely.

Why is there a comma before aber in German?

In German, you must put a comma between two main clauses that are joined by conjunctions like aber, denn, sondern, und, oder when each side could stand alone as a full sentence.

Here we have two full main clauses:

Ich bin mit meinem Ergebnis unzufrieden.
(Aber) dafür kenne ich jetzt meine Schwächen besser.

Each has its own subject and finite verb, so German spelling rules require a comma:

Ich bin mit meinem Ergebnis unzufrieden, aber dafür kenne ich jetzt meine Schwächen besser.

In English, a comma before but is often optional or a style choice; in German, in this case, it’s a rule.

Could we say aber jetzt kenne ich meine Schwächen besser instead of aber dafür kenne ich jetzt meine Schwächen besser?

Yes, that is grammatically correct, but the nuance changes slightly.

aber dafür kenne ich jetzt meine Schwächen besser.
→ highlights a kind of compensation or trade-off (“but in return / but at least…”).
aber jetzt kenne ich meine Schwächen besser.
→ simply contrasts the time before and after (“but now I know my weaknesses better”), without the same “in return” flavor.

Both are fine; dafür adds the idea that this new knowledge partly compensates for the bad result.

Is unzufrieden an adjective or a verb form, and how does it work with sein?

unzufrieden is an adjective meaning dissatisfied / not satisfied.

In the sentence:

Ich bin mit meinem Ergebnis unzufrieden.

we have:

bin = 1st person singular of sein (to be) → the verb
unzufrieden = adjective predicative, describing the subject ich

This is the normal pattern:

Ich bin müde. – I am tired.
Ich bin glücklich. – I am happy.
Ich bin unzufrieden. – I am dissatisfied.

So sein + Adjektiv is how you express “to be + adjective” in German.