"по-третє" meaning in Ukrainian

{
  "forms": [
    {
      "form": "по-тре́тє",
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "po-trétje",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "по-тре́тє"
      },
      "expansion": "по-тре́тє • (po-trétje)",
      "name": "uk-adv"
    }
  ],
  "lang": "Ukrainian",
  "lang_code": "uk",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Ukrainian entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Ukrainian links with redundant alt parameters",
          "parents": [
            "Links with redundant alt parameters",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "uk",
          "name": "Three",
          "orig": "uk:Three",
          "parents": [
            "Numbers",
            "All topics",
            "Terms by semantic function",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "thirdly"
      ],
      "id": "en-по-третє-uk-adv-a~LBRirn",
      "links": [
        [
          "thirdly",
          "thirdly"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[pɔ ˈtrɛtʲe]"
    }
  ],
  "word": "по-третє"
}

{
  "forms": [
    {
      "form": "по-тре́тє",
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "po-trétje",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "по-тре́тє"
      },
      "expansion": "по-тре́тє • (po-trétje)",
      "name": "uk-adv"
    }
  ],
  "lang": "Ukrainian",
  "lang_code": "uk",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        "Ukrainian adverbs",
        "Ukrainian entries with incorrect language header",
        "Ukrainian lemmas",
        "Ukrainian links with redundant alt parameters",
        "Ukrainian multiword terms",
        "Ukrainian sequence adverbs",
        "Ukrainian terms with IPA pronunciation",
        "uk:Three"
      ],
      "glosses": [
        "thirdly"
      ],
      "links": [
        [
          "thirdly",
          "thirdly"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[pɔ ˈtrɛtʲe]"
    }
  ],
  "word": "по-третє"
}