"5-O" meaning in English

{
  "etymology_text": "Referring to the television series Hawaii Five-O.",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "5-O (uncountable)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Law enforcement",
          "orig": "en:Law enforcement",
          "parents": [
            "Crime prevention",
            "Emergency services",
            "Law",
            "Crime",
            "Public safety",
            "Justice",
            "Criminal law",
            "Society",
            "Public administration",
            "Security",
            "All topics",
            "Government",
            "Fundamental",
            "Politics"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The police."
      ],
      "id": "en-5-O-en-noun-ArbpzIom",
      "links": [
        [
          "police",
          "police"
        ]
      ],
      "qualifier": "street slang",
      "raw_glosses": [
        "(US, street slang) The police."
      ],
      "synonyms": [
        {
          "word": "five-o"
        }
      ],
      "tags": [
        "US",
        "uncountable"
      ],
      "wikipedia": [
        "Hawaii Five-O"
      ]
    }
  ],
  "word": "5-O"
}

{
  "etymology_text": "Referring to the television series Hawaii Five-O.",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "5-O (uncountable)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "American English",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English slang",
        "English terms spelled with numbers",
        "English uncountable nouns",
        "en:Law enforcement"
      ],
      "glosses": [
        "The police."
      ],
      "links": [
        [
          "police",
          "police"
        ]
      ],
      "qualifier": "street slang",
      "raw_glosses": [
        "(US, street slang) The police."
      ],
      "tags": [
        "US",
        "uncountable"
      ],
      "wikipedia": [
        "Hawaii Five-O"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "five-o"
    }
  ],
  "word": "5-O"
}