Translation:I walk fifty meters north.
Instructions have a different sentence form, and the verb might change.
When we see sentences like this, usually we assume the speaker is the one referred to.
E.g: クレアちゃんは、朝学校にどうやって行きましたか? (How do you get to school in the morning?)
五十メーター北に歩きます。(I walk 50 meters north).
It makes sense, because we're answering a question. If we talk about someone else, however, it's either an instruction or an odd statement. It's hard to find a situation where you say something like "you walk 50 meters north" in English without giving an instruction. This would be more like an instruction:
その学校にどうやって行きますか?(How do I get to the school?)
五十メーター北に歩きてください。(You walk 50 meters north.)
Words in katakana, aka loan words, are not just "English words." They are mostly a Japanese pronunciation based on how the word was spelt. There are a good many others, such as allergy (アレルギー) being pronounced with a clumsy double l/r and a hard g, because that's how it looked it like was from the letters.
Also, you'll come across others that are not English (パン for bread), or are being used differently from their meaning in English, such as ハンドル referring to a car's steering wheel, and nothing to do with doors.