"Gates of Hercules" meaning in English

{
  "forms": [
    {
      "form": "the Gates of Hercules",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "def": "1",
        "head": "Gates of Hercules"
      },
      "expansion": "the Gates of Hercules",
      "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"
        }
      ],
      "examples": [
        {
          "ref": "1968, Joseph Campbell, The Hero with a Thousand Faces, 2nd edition, London: Fontana Press, published 1993, page 14",
          "text": "The bold little ships even broke through the Gates of Hercules to the open ocean, coasting then northward to take the gold of Ireland and the tin of Cornwall, as well as southward, around the bulge of Senegal, to remote Yorubaland and the distant marts of ivory, gold, and slaves.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Two rocky eminences on either side of the Strait of Gibraltar."
      ],
      "id": "en-Gates_of_Hercules-en-name-kcOA55Io",
      "links": [
        [
          "rocky",
          "rocky"
        ],
        [
          "eminence",
          "eminence"
        ],
        [
          "Strait of Gibraltar",
          "Strait of Gibraltar"
        ]
      ]
    }
  ],
  "word": "Gates of Hercules"
}

{
  "forms": [
    {
      "form": "the Gates of Hercules",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "def": "1",
        "head": "Gates of Hercules"
      },
      "expansion": "the Gates of Hercules",
      "name": "en-proper noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English proper nouns",
        "English terms with quotations",
        "English uncountable nouns"
      ],
      "examples": [
        {
          "ref": "1968, Joseph Campbell, The Hero with a Thousand Faces, 2nd edition, London: Fontana Press, published 1993, page 14",
          "text": "The bold little ships even broke through the Gates of Hercules to the open ocean, coasting then northward to take the gold of Ireland and the tin of Cornwall, as well as southward, around the bulge of Senegal, to remote Yorubaland and the distant marts of ivory, gold, and slaves.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Two rocky eminences on either side of the Strait of Gibraltar."
      ],
      "links": [
        [
          "rocky",
          "rocky"
        ],
        [
          "eminence",
          "eminence"
        ],
        [
          "Strait of Gibraltar",
          "Strait of Gibraltar"
        ]
      ]
    }
  ],
  "word": "Gates of Hercules"
}