I was seeing some posts in the forum and I found a phrase that called my attention
えいがはあまり見ません。- I do not watch movies
the guy asked why it has an ''wa'' instead of'' wo.
The guy who answered his question. Told him that ''Because えいが is the topic. If the topic is the direct object, は replaces を''
and I don't understand it at all. If I say ''I eat fish'' I have to use ''wo''. but If I say ''I don't eat fish'' I have to use ''wa'' and I don't understand why Someone can explain me please? I am learning since yesterday and particles are really hard for me.
Japanese has fundamentally different rules of grammar than English. Let's consider these four parts of a sentence. Topic, subject, object, and verb. In English, we usually omit the topic. When we include it, we get sentences like, "As for me, I like pizza." When we omit the subject or object in a sentence though, it sounds strange. If I said "As for me, like pizza" you might think I was trying to be cute.
Japanese is different. Japanese indicates the verb by putting it at the end and conjugating. Japanese indicates topic, subject, and object with particles は、を、& が respectively. If something is the topic and the subject, it's usually indicated as the topic with は and not as the subject. Sentences like "as for me, pizza like" are usual in Japanese, where a sentence like "I like pizza" is emphatic.
Negativity has nothing to do with it. えいがはあまり見ません means "as for movies, don't really watch them" with the subject being assumed. えいがは見ます means "as for movies, watch them."
For particles in general, I try to think them as inflections, suffixes we add to a word to help us know their role in the sentence. Sort of like who and whom. It doesn't make them easier... but it makes them less strange feeling. For me at least.
I started learning 日本語 (Nihongo - Japanese) on Memrise first. Here is what I learned there about は and を. If you break the sentence down to a literal translation, I believe it would be: Movie (topic) watch not.
は (Ha/Wa) - In the example above, は (wa) is the topic particle. Letting you know that えいが is the topic of the sentence. Basically saying, "I'm talking about a movie in my sentence."
を(Wo/O) - In this case, を (o) is an object particle. Letting you know that えいが is an object in my sentence. I would believe a sentence could be, "I have a movie (to watch)." Something along those lines.
I hope that clarifies it for you. This is how I understand it at least and I may not be entirely right. I've been using Memrise, and now Duo, for around 3-4+ months to study Japanese so take my explanation lightly as I'm still learning as well.
I've been curious about the distinction in usage of wo vs. wa. I found this video a while back that was helpful for me. Maybe it will help!
I'm still learning, but I think you could say
"About fish, to eat" - I eat fish if the context makes it clear.
If you only have a few words in your sentence, then it should be understood by context which one is the object anyway. And は is generally prefered over を it seems.