"première pierre" meaning in French

{
  "forms": [
    {
      "form": "premières pierres",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "première pierre f (plural premières pierres)",
      "name": "fr-noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "French entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "fr",
          "name": "Architecture",
          "orig": "fr:Architecture",
          "parents": [
            "Applied sciences",
            "Art",
            "Sciences",
            "Culture",
            "All topics",
            "Society",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "english": "to lay the first stone",
          "text": "poser la première pierre",
          "type": "example"
        }
      ],
      "glosses": [
        "foundation stone"
      ],
      "id": "en-première_pierre-fr-noun-z7xDm~6N",
      "links": [
        [
          "architecture",
          "architecture"
        ],
        [
          "foundation stone",
          "foundation stone"
        ]
      ],
      "raw_glosses": [
        "(architecture) foundation stone"
      ],
      "tags": [
        "feminine"
      ],
      "topics": [
        "architecture"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/pʁə.mjɛʁ pjɛʁ/"
    }
  ],
  "word": "première pierre"
}

{
  "forms": [
    {
      "form": "premières pierres",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "première pierre f (plural premières pierres)",
      "name": "fr-noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "French countable nouns",
        "French entries with incorrect language header",
        "French feminine nouns",
        "French lemmas",
        "French multiword terms",
        "French nouns",
        "French terms with IPA pronunciation",
        "French terms with usage examples",
        "fr:Architecture"
      ],
      "examples": [
        {
          "english": "to lay the first stone",
          "text": "poser la première pierre",
          "type": "example"
        }
      ],
      "glosses": [
        "foundation stone"
      ],
      "links": [
        [
          "architecture",
          "architecture"
        ],
        [
          "foundation stone",
          "foundation stone"
        ]
      ],
      "raw_glosses": [
        "(architecture) foundation stone"
      ],
      "tags": [
        "feminine"
      ],
      "topics": [
        "architecture"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/pʁə.mjɛʁ pjɛʁ/"
    }
  ],
  "word": "première pierre"
}