"R9" meaning in English

{
  "etymology_text": "From Ronaldo's initial (R) and his playing number (9).",
  "head_templates": [
    {
      "args": {},
      "expansion": "R9",
      "name": "en-proper noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Football (soccer)",
          "orig": "en:Football (soccer)",
          "parents": [
            "Football",
            "Ball games",
            "Sports",
            "Human activity",
            "Human behaviour",
            "Human",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Nicknames of individuals",
          "orig": "en:Nicknames of individuals",
          "parents": [
            "Individuals",
            "Nicknames",
            "People",
            "Names",
            "Human",
            "All topics",
            "Proper nouns",
            "Terms by semantic function",
            "Fundamental",
            "Nouns",
            "Lemmas"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Ronaldo (a Brazilian footballer)"
      ],
      "id": "en-R9-en-name-5TnDT3X7",
      "links": [
        [
          "soccer",
          "soccer"
        ]
      ],
      "raw_glosses": [
        "(soccer) Ronaldo (a Brazilian footballer)"
      ],
      "topics": [
        "ball-games",
        "games",
        "hobbies",
        "lifestyle",
        "soccer",
        "sports"
      ]
    }
  ],
  "word": "R9"
}

{
  "etymology_text": "From Ronaldo's initial (R) and his playing number (9).",
  "head_templates": [
    {
      "args": {},
      "expansion": "R9",
      "name": "en-proper noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
      "categories": [
        "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:Football (soccer)",
        "en:Nicknames of individuals"
      ],
      "glosses": [
        "Ronaldo (a Brazilian footballer)"
      ],
      "links": [
        [
          "soccer",
          "soccer"
        ]
      ],
      "raw_glosses": [
        "(soccer) Ronaldo (a Brazilian footballer)"
      ],
      "topics": [
        "ball-games",
        "games",
        "hobbies",
        "lifestyle",
        "soccer",
        "sports"
      ]
    }
  ],
  "word": "R9"
}