"5280" meaning in English

{
  "etymology_text": "Denver is known as the \"Mile High City\", and there are 5,280 feet in a mile.",
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  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
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          "name": "English entries with incorrect language header",
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        },
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          "kind": "other",
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          "name": "City nicknames",
          "orig": "en:City nicknames",
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        {
          "kind": "other",
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          "name": "Colorado, USA",
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        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Denver",
          "orig": "en:Denver",
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      ],
      "glosses": [
        "Denver, Colorado."
      ],
      "id": "en-5280-en-name-Hypa8zNm",
      "links": [
        [
          "Denver",
          "Denver"
        ],
        [
          "Colorado",
          "Colorado"
        ]
      ]
    }
  ],
  "word": "5280"
}

{
  "etymology_text": "Denver is known as the \"Mile High City\", and there are 5,280 feet in a mile.",
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      "expansion": "5280",
      "name": "en-prop"
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  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
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        "English entries with incorrect language header",
        "English lemmas",
        "English proper nouns",
        "English terms spelled with numbers",
        "English uncountable nouns",
        "English words without vowels",
        "Pages with 1 entry",
        "Pages with entries",
        "en:City nicknames",
        "en:Colorado, USA",
        "en:Denver"
      ],
      "glosses": [
        "Denver, Colorado."
      ],
      "links": [
        [
          "Denver",
          "Denver"
        ],
        [
          "Colorado",
          "Colorado"
        ]
      ]
    }
  ],
  "word": "5280"
}