は --> the element before it is the theme of the sentence. Often this is the doer (subject).
を --> the element before it is the person/thing affected by the action (direct object).
- knowing how verbs look like and where they are placed in sentences
それで, 英雄神 マルドウク は 海の女神 チアマトと 彼女が 生んだ 11種の竜を 相手に たった 一人で 戦いを挑みました。
戦いを挑みました --> The main verb is generally placed at the end of a sentence. The bit marked in red is a characteristic verb ending; these endings will also help you spot the verbs.
- knowing how nouns (= words referring to people, animals or things like "Mary" or "dog") look like
それで, 英雄神 マルドウク は 海の女神 チアマトと 彼女が 生んだ 11種の竜を 相手に たった 一人で 戦いを挑みました。
英雄神, 海の女神, 竜 --> I only marked the most important nouns referring to the doer (subject) and the people/things affected by the action (direct objects). If you want to spot the nouns in a sentence you have to look for the Chinese characters (Kanji).
Now, if we look closely, we'll see that the basic pattern of our sentence seems to be:
noun は noun を verb.
Once we've found this pattern, we can look up unknown words in a dictionary and fill this pattern with meaning.
Here is a simplified version of our sentence:
それで, 英雄神 は 海の女神 を 戦いを挑みました。
If you look up the words, you come up with--->
それで = thereupon
英雄神 は = the highest god (subject)
海の女神 を = the sea goddess (object)
戦いを挑みました。= challenged to fight (verb)
So, the meaning of the sentence is something like:
Thereupon, the highest god challenged the sea goddess to fight (against him).
That wasn't really all that difficult, right??
Ok, so now all you'll have to do is learn:
- all about grammatical particles
- how verbs, nouns and adjectives look like and how to spot them in a sentence
- Japanese characters (at least some of them...)
- how to look up words in a dictionary
- and probably a whole lot of other things I forgot to mention...^^