"línea roja" meaning in Spanish

{
  "etymology_templates": [
    {
      "args": {
        "1": "es",
        "2": "en",
        "3": "red line"
      },
      "expansion": "Calque of English red line",
      "name": "calque"
    }
  ],
  "etymology_text": "Calque of English red line.",
  "forms": [
    {
      "form": "líneas rojas",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "línea roja f (plural líneas rojas)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Spanish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "red line (a boundary or limit that should not be crossed)"
      ],
      "id": "en-línea_roja-es-noun-Dq2VLwiE",
      "links": [
        [
          "red line",
          "red line"
        ],
        [
          "boundary",
          "boundary#English"
        ],
        [
          "limit",
          "limit#English"
        ]
      ],
      "tags": [
        "feminine"
      ]
    }
  ],
  "word": "línea roja"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "es",
        "2": "en",
        "3": "red line"
      },
      "expansion": "Calque of English red line",
      "name": "calque"
    }
  ],
  "etymology_text": "Calque of English red line.",
  "forms": [
    {
      "form": "líneas rojas",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "línea roja f (plural líneas rojas)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Pages with 1 entry",
        "Pages with entries",
        "Spanish countable nouns",
        "Spanish entries with incorrect language header",
        "Spanish feminine nouns",
        "Spanish lemmas",
        "Spanish multiword terms",
        "Spanish nouns",
        "Spanish terms calqued from English",
        "Spanish terms derived from English"
      ],
      "glosses": [
        "red line (a boundary or limit that should not be crossed)"
      ],
      "links": [
        [
          "red line",
          "red line"
        ],
        [
          "boundary",
          "boundary#English"
        ],
        [
          "limit",
          "limit#English"
        ]
      ],
      "tags": [
        "feminine"
      ]
    }
  ],
  "word": "línea roja"
}