"-∅" meaning in Skolt Sami

{
  "etymology_templates": [
    {
      "args": {
        "1": "sms",
        "2": "smi-pro",
        "3": "*-ō"
      },
      "expansion": "Proto-Samic *-ō",
      "name": "inh"
    }
  ],
  "etymology_text": "From Proto-Samic *-ō.",
  "head_templates": [
    {
      "args": {
        "1": "sms",
        "2": "suffix",
        "cat2": "noun-forming suffixes"
      },
      "expansion": "-∅",
      "name": "head"
    }
  ],
  "lang": "Skolt Sami",
  "lang_code": "sms",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Pages with 10 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Skolt Sami entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Skolt Sami terms in nonstandard scripts",
          "parents": [
            "Terms in nonstandard scripts",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Forms result or action nouns from verbs."
      ],
      "id": "en--∅-sms-suffix-YkLy-uhl",
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "-∅"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "sms",
        "2": "smi-pro",
        "3": "*-ō"
      },
      "expansion": "Proto-Samic *-ō",
      "name": "inh"
    }
  ],
  "etymology_text": "From Proto-Samic *-ō.",
  "head_templates": [
    {
      "args": {
        "1": "sms",
        "2": "suffix",
        "cat2": "noun-forming suffixes"
      },
      "expansion": "-∅",
      "name": "head"
    }
  ],
  "lang": "Skolt Sami",
  "lang_code": "sms",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        "Pages with 10 entries",
        "Pages with entries",
        "Skolt Sami entries with incorrect language header",
        "Skolt Sami lemmas",
        "Skolt Sami noun-forming suffixes",
        "Skolt Sami suffixes",
        "Skolt Sami terms derived from Proto-Samic",
        "Skolt Sami terms in nonstandard scripts",
        "Skolt Sami terms inherited from Proto-Samic"
      ],
      "glosses": [
        "Forms result or action nouns from verbs."
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "-∅"
}