"spare room" meaning in English

{
  "forms": [
    {
      "form": "spare rooms",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "spare room (plural spare rooms)",
      "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": "Rooms",
          "orig": "en:Rooms",
          "parents": [
            "Buildings and structures",
            "Architecture",
            "Applied sciences",
            "Art",
            "Sciences",
            "Culture",
            "All topics",
            "Society",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2020 September 1, Tom Lamont, “The butcher's shop that lasted 300 years (give or take)”, in The Guardian",
          "text": "His entire adult life he had lived in the two-bed flat above the shop, sharing the space with his parents. Frank was in the spare room at the back. His parents had the master bedroom, with a big sash window that overlooked the high street.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "guest room"
      ],
      "id": "en-spare_room-en-noun-Y9qzvfcZ",
      "links": [
        [
          "guest room",
          "guest room"
        ]
      ]
    }
  ],
  "word": "spare room"
}

{
  "forms": [
    {
      "form": "spare rooms",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "spare room (plural spare rooms)",
      "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 with quotations",
        "en:Rooms"
      ],
      "examples": [
        {
          "ref": "2020 September 1, Tom Lamont, “The butcher's shop that lasted 300 years (give or take)”, in The Guardian",
          "text": "His entire adult life he had lived in the two-bed flat above the shop, sharing the space with his parents. Frank was in the spare room at the back. His parents had the master bedroom, with a big sash window that overlooked the high street.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "guest room"
      ],
      "links": [
        [
          "guest room",
          "guest room"
        ]
      ]
    }
  ],
  "word": "spare room"
}