"null-subject language" meaning in English

{
  "forms": [
    {
      "form": "null-subject languages",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "null-subject language (plural null-subject languages)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with topic categories using raw markup",
          "parents": [
            "Entries with topic categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Linguistics",
          "orig": "en:Linguistics",
          "parents": [
            "Language",
            "Social sciences",
            "Communication",
            "Sciences",
            "Society",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A pro-drop language that may frequently leave out subject pronouns that are implied by verbal conjugations, such as Persian, Hebrew, and many Slavic and Romance languages."
      ],
      "id": "en-null-subject_language-en-noun-aIfLSFes",
      "links": [
        [
          "pro-drop language",
          "pro-drop language"
        ],
        [
          "subject",
          "subject"
        ],
        [
          "conjugation",
          "conjugation"
        ],
        [
          "Persian",
          "Persian"
        ],
        [
          "Hebrew",
          "Hebrew"
        ],
        [
          "Slavic",
          "Slavic"
        ],
        [
          "Romance language",
          "Romance language"
        ]
      ],
      "wikipedia": [
        "null-subject language"
      ]
    }
  ],
  "word": "null-subject language"
}

{
  "forms": [
    {
      "form": "null-subject languages",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "null-subject language (plural null-subject languages)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with topic categories using raw markup",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys",
        "en:Linguistics"
      ],
      "glosses": [
        "A pro-drop language that may frequently leave out subject pronouns that are implied by verbal conjugations, such as Persian, Hebrew, and many Slavic and Romance languages."
      ],
      "links": [
        [
          "pro-drop language",
          "pro-drop language"
        ],
        [
          "subject",
          "subject"
        ],
        [
          "conjugation",
          "conjugation"
        ],
        [
          "Persian",
          "Persian"
        ],
        [
          "Hebrew",
          "Hebrew"
        ],
        [
          "Slavic",
          "Slavic"
        ],
        [
          "Romance language",
          "Romance language"
        ]
      ],
      "wikipedia": [
        "null-subject language"
      ]
    }
  ],
  "word": "null-subject language"
}