"product rule" meaning in English

{
  "head_templates": [
    {
      "args": {},
      "expansion": "product rule",
      "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"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Calculus",
          "orig": "en:Calculus",
          "parents": [
            "Mathematical analysis",
            "Mathematics",
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Mathematics",
          "orig": "en:Mathematics",
          "parents": [
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A formula used to find the derivatives of products of two or more functions: (f·g)'=f'·g+f·g',!"
      ],
      "id": "en-product_rule-en-name-hMue4uQx",
      "links": [
        [
          "mathematics",
          "mathematics"
        ],
        [
          "formula",
          "formula"
        ],
        [
          "derivative",
          "derivative"
        ],
        [
          "product",
          "product"
        ],
        [
          "function",
          "function"
        ]
      ],
      "raw_glosses": [
        "(mathematics) A formula used to find the derivatives of products of two or more functions: (f·g)'=f'·g+f·g',!"
      ],
      "topics": [
        "mathematics",
        "sciences"
      ],
      "wikipedia": [
        "product rule"
      ]
    }
  ],
  "word": "product rule"
}

{
  "head_templates": [
    {
      "args": {},
      "expansion": "product rule",
      "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 uncountable nouns",
        "en:Calculus",
        "en:Mathematics"
      ],
      "glosses": [
        "A formula used to find the derivatives of products of two or more functions: (f·g)'=f'·g+f·g',!"
      ],
      "links": [
        [
          "mathematics",
          "mathematics"
        ],
        [
          "formula",
          "formula"
        ],
        [
          "derivative",
          "derivative"
        ],
        [
          "product",
          "product"
        ],
        [
          "function",
          "function"
        ]
      ],
      "raw_glosses": [
        "(mathematics) A formula used to find the derivatives of products of two or more functions: (f·g)'=f'·g+f·g',!"
      ],
      "topics": [
        "mathematics",
        "sciences"
      ],
      "wikipedia": [
        "product rule"
      ]
    }
  ],
  "word": "product rule"
}