"-gen" meaning in Garo

{
  "head_templates": [
    {
      "args": {
        "1": "grt",
        "2": "suffix"
      },
      "expansion": "-gen",
      "name": "head"
    }
  ],
  "lang": "Garo",
  "lang_code": "grt",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Garo entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "future tense suffix"
      ],
      "id": "en--gen-grt-suffix-Ha16iimG",
      "related": [
        {
          "tags": [
            "Mandi"
          ],
          "word": "-noa"
        }
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "-gen"
}

{
  "head_templates": [
    {
      "args": {
        "1": "grt",
        "2": "suffix"
      },
      "expansion": "-gen",
      "name": "head"
    }
  ],
  "lang": "Garo",
  "lang_code": "grt",
  "pos": "suffix",
  "related": [
    {
      "tags": [
        "Mandi"
      ],
      "word": "-noa"
    }
  ],
  "senses": [
    {
      "categories": [
        "Garo entries with incorrect language header",
        "Garo lemmas",
        "Garo suffixes"
      ],
      "glosses": [
        "future tense suffix"
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "-gen"
}

{
  "called_from": "form_descriptions/1698",
  "msg": "unrecognized head form: A·chik",
  "path": [
    "-gen"
  ],
  "section": "Garo",
  "subsection": "suffix",
  "title": "-gen",
  "trace": ""
}