"life span" meaning in English

{
  "forms": [
    {
      "form": "life spans",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "life span (plural life spans)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "lifespan"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1962 October, Brian Haresnape, “Focus on B.R. passenger stations”, in Modern Railways, page 250",
          "text": "The working life span of a passenger carriage, on average, is between 30 and 35 years, so a steady replacement takes place quite naturally. The life span of a station, however, cannot be so easily reckoned, for it depends largely on the rehabilitation and upkeep of the existing structures.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Alternative spelling of lifespan."
      ],
      "id": "en-life_span-en-noun-JNQS8onP",
      "links": [
        [
          "lifespan",
          "lifespan#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "life span"
}

{
  "forms": [
    {
      "form": "life spans",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "life span (plural life spans)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "lifespan"
        }
      ],
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "1962 October, Brian Haresnape, “Focus on B.R. passenger stations”, in Modern Railways, page 250",
          "text": "The working life span of a passenger carriage, on average, is between 30 and 35 years, so a steady replacement takes place quite naturally. The life span of a station, however, cannot be so easily reckoned, for it depends largely on the rehabilitation and upkeep of the existing structures.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Alternative spelling of lifespan."
      ],
      "links": [
        [
          "lifespan",
          "lifespan#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "life span"
}