"I prefer the translation from German."
Translation:Mi preferas la tradukon el la germana.
El is the opposite of Al. El means out from and Al means to or toward. The key is that they both indicate direction. De indicates possesion or quality. Therefore el is used in this sentance to show a change from one translation to another. Someone else please correct me if I am wrong. Tim?
I believe 'el' would be used to indicate a translation of the same piece from German, as opposed to translation of that piece from another language. 'De' would imply that one prefers the translation of German over whatever language the piece is in. However, I could be incorrect, so anybody can feel free to correct me, I'd thank you for the help of distinction as well!
Just to expand on johnmue's answer, which is entirely correct: most languages in Esperanto are referred to with adjectives, e.g. "la angla", "la germana", "la rusa", "la ĉina", etc. It means "la angla lingvo", "la germana lingvo" etc. but repeating "lingvo" each time is superfluous. In each of these cases, the o-word refers to a person of the given nationality ("anglo" = "an English person", "ĉino" = "a Chinese person" etc.)
There are a few which are different, the obvious one being Esperanto itself. There is no Esperanto people, race or nationality, so it doesn't really make sense to say "la esperanta lingvo"; it's just "Esperanto".