"400 metres" meaning in English

{
  "forms": [
    {
      "form": "400 metres",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "400 metres"
      },
      "expansion": "400 metres (plural 400 metres)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Athletics",
          "orig": "en:Athletics",
          "parents": [
            "Sports",
            "Human activity",
            "Human behaviour",
            "Human",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A sprint race over 400 metres."
      ],
      "id": "en-400_metres-en-noun-lR67fz2q",
      "links": [
        [
          "athletics",
          "athletics"
        ],
        [
          "sprint",
          "sprint"
        ],
        [
          "metres",
          "metres"
        ]
      ],
      "raw_glosses": [
        "(athletics) A sprint race over 400 metres."
      ],
      "synonyms": [
        {
          "tags": [
            "US"
          ],
          "word": "400 meters"
        }
      ],
      "topics": [
        "athletics",
        "hobbies",
        "lifestyle",
        "sports"
      ],
      "translations": [
        {
          "code": "fi",
          "lang": "Finnish",
          "sense": "sprint race over 400 metres",
          "word": "400 metrin juoksu"
        },
        {
          "code": "fr",
          "lang": "French",
          "sense": "sprint race over 400 metres",
          "tags": [
            "masculine"
          ],
          "word": "400 mètres"
        },
        {
          "code": "ro",
          "lang": "Romanian",
          "sense": "sprint race over 400 metres",
          "word": "400 metri"
        }
      ],
      "wikipedia": [
        "400 metres"
      ]
    }
  ],
  "word": "400 metres"
}

{
  "forms": [
    {
      "form": "400 metres",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "400 metres"
      },
      "expansion": "400 metres (plural 400 metres)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms spelled with numbers",
        "en:Athletics"
      ],
      "glosses": [
        "A sprint race over 400 metres."
      ],
      "links": [
        [
          "athletics",
          "athletics"
        ],
        [
          "sprint",
          "sprint"
        ],
        [
          "metres",
          "metres"
        ]
      ],
      "raw_glosses": [
        "(athletics) A sprint race over 400 metres."
      ],
      "topics": [
        "athletics",
        "hobbies",
        "lifestyle",
        "sports"
      ],
      "wikipedia": [
        "400 metres"
      ]
    }
  ],
  "synonyms": [
    {
      "tags": [
        "US"
      ],
      "word": "400 meters"
    }
  ],
  "translations": [
    {
      "code": "fi",
      "lang": "Finnish",
      "sense": "sprint race over 400 metres",
      "word": "400 metrin juoksu"
    },
    {
      "code": "fr",
      "lang": "French",
      "sense": "sprint race over 400 metres",
      "tags": [
        "masculine"
      ],
      "word": "400 mètres"
    },
    {
      "code": "ro",
      "lang": "Romanian",
      "sense": "sprint race over 400 metres",
      "word": "400 metri"
    }
  ],
  "word": "400 metres"
}