"právě tehdy, když" meaning in Czech

{
  "head_templates": [
    {
      "args": {
        "1": "cs",
        "2": "conjunction"
      },
      "expansion": "právě tehdy, když",
      "name": "head"
    }
  ],
  "lang": "Czech",
  "lang_code": "cs",
  "pos": "conj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Czech entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "cs",
          "name": "Logic",
          "orig": "cs:Logic",
          "parents": [
            "Formal sciences",
            "Philosophy",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "if and only if"
      ],
      "id": "en-právě_tehdy,_když-cs-conj-69uIsb~t",
      "links": [
        [
          "if and only if",
          "if and only if"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[praːvjɛ tɛɦdɪ ɡdɪʃ]"
    }
  ],
  "word": "právě tehdy, když"
}

{
  "head_templates": [
    {
      "args": {
        "1": "cs",
        "2": "conjunction"
      },
      "expansion": "právě tehdy, když",
      "name": "head"
    }
  ],
  "lang": "Czech",
  "lang_code": "cs",
  "pos": "conj",
  "senses": [
    {
      "categories": [
        "Czech conjunctions",
        "Czech entries with incorrect language header",
        "Czech lemmas",
        "Czech multiword terms",
        "Czech terms with IPA pronunciation",
        "cs:Logic"
      ],
      "glosses": [
        "if and only if"
      ],
      "links": [
        [
          "if and only if",
          "if and only if"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[praːvjɛ tɛɦdɪ ɡdɪʃ]"
    }
  ],
  "word": "právě tehdy, když"
}