- 「上を向いて歩こう」≈Let's walk upwards. (Google translation)
- 「涙が溢れないように、上を向いて歩こう」≈ Let's walk upwards so that tears will not overflow. (Google translation)
But if you know what "向いて(むいて)" means, it is a bit different from machine translation.
You may have heard "こっち向いて", which means turning your face toward a certain place.
So, "上を向いて歩こう" is to make you face toward an uncertain place but above, and then walk.
歩こう is the volitional form of 歩く. The meaning of this sentence is "Let's walk."
In fact, you know, you may find that at least in Anime, this phrase rarely appears. For example, you often see "行こう,行かない,行ける", but you rarely see "歩こう, 歩かない, 歩ける". I mean, it's not that these are wrong, but it's really rare. As a result, you may not think of what it is when you hear it for the first time, and may think it is a new word.
Conjugation of "歩く"
- Imperfective (未然形): 歩か
- Continuative (連用形): 歩き
- Terminal (終止形): 歩く
- Attributive (連体形): 歩く
- Hypothetical (仮定形): 歩け
- Passive: 歩かれる
- Causative: 歩かせる 歩かす
- Potential: 歩ける
- Volitional: 歩こう
- Negative: 歩かない
- Negative continuative: 歩かず
- Formal: 歩きます
- Perfective: 歩いた
- Conjunctive: 歩いて
- Hypothetical conditional: 歩けば