Translation:It can also be searched by author and work.
I know there's a better link that explains this little better but I can't find it right now. Here's a list of some of those verbs. http://www.elearnspanishlanguage.com/grammar/verb/verbswithprep-none2.html
When you are talking about two different searches,then it is "by author or by work" (I would say title, but they won't accept that here.) If you are looking for a particular author then you would say "look for". So, searching by author is a way to look for a book written by a particular author.
...and I would say "You can also search by author and work." , it depends what you are emphasizing. "you also" not just I, "can also search" focuses on the action being also possible, "Also" at the beginning of the sentence, is like saying "and another thing" or "besides what I already told you" The fact is that "tambien" can also be put elsewhere.
There are lists of authors and lists of works by title. They just wanted us to learn this word "obra", but we would normally say by title. We would say "search by author and title", but they insist on "work" for "obra". We look for the title of the work. It is an expression that we just say "title" while they just say "work".. Notice we don't say "the name of the author."
"Se" by itself usually means "one" or more informally the general sense of "you" or "we" meaning everyone or all. For example: No se hace eso!" = You don't do that! or One doesn't do that or We don't do that!
It can also be reflexive with an el or ella to which it can refer in the sense of he, himself or she, herself . Context is very important, but in a single sentence without context, go for the meaning "one".
Not much difference when you use the same preposition, but it is "search by" which is a method of looking for something. When you search by author, you are using a list of authors or a search engine which can go through an online list of authors. “Look for” requires a noun to follow directly afterwards so to say this you would say “look for a book by author and title (work is used instead of title in this sentence).
https://www.thoughtco.com/impersonal-verb-spanish-3079905 Spanish uses the reflexive when we would use the passive voice.
It will also accept "Also you can search by author and work." We did learn the form to use with usted. We have even had reflexive verbs before. You are learning right now by doing which is what Duolingo often does. They use a reflexive form here for when we are likely to use the passive voice. https://www.thoughtco.com/impersonal-verb-spanish-3079905
After being told I was wrong twice with what should be correct answers, according to the hints one gets when hovering over the words, I typed the EXACT translation given as the correct answer. Still I was told the answer is wrong. This is clearly an mistake by duolingo.