To use Online Translation so that it can help you the most, it is necessary to understand a little how online translation sites work.
Imagine, for a moment, if you were a computer. Perhaps the first way you might try to translate is by taking each of the words in one language and finding the word in the second language. After finding the words, you would then put them in the proper order. So for
I like cats
you would get
watashi suki neko
which you would then put in the correct order and get
watashi (ha) neko (ga) suki.
Already, you can see that it would be important to add some words to the Japanese to make it understandable. But consider the other direction. In idiomatic Japanese, "I like cats" would be
猫が好き。
Our computer, without any context, would not know _who_ likes cats. So, in order to help the computer/translation software, we may want to make the Japanese more like English to help get a more natural translation.
This is very important with signage. Translating a longer passage makes it clear who is being talked about, but signs are short, often only one or two sentences. So adjusting what you want to translate is an easy way to get better, more understandable signs.