"ain't that the truth" meaning in English

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "phrase",
        "head": "ain't that the truth?"
      },
      "expansion": "ain't that the truth?",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "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 language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "name": "English rhetorical questions",
          "parents": [
            "Rhetorical questions",
            "Idioms",
            "Questions",
            "Sentences",
            "Figures of speech",
            "Terms by semantic function",
            "Rhetoric",
            "Language",
            "Communication",
            "All topics",
            "Fundamental"
          ],
          "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"
        }
      ],
      "glosses": [
        "That is very true; I agree (often with a gloomy or pessimistic tone)."
      ],
      "id": "en-ain't_that_the_truth-en-phrase-~w1tbwWj",
      "raw_glosses": [
        "(colloquial) That is very true; I agree (often with a gloomy or pessimistic tone)."
      ],
      "tags": [
        "colloquial"
      ]
    }
  ],
  "word": "ain't that the truth"
}

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "phrase",
        "head": "ain't that the truth?"
      },
      "expansion": "ain't that the truth?",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "senses": [
    {
      "categories": [
        "English colloquialisms",
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English lemmas",
        "English multiword terms",
        "English phrases",
        "English rhetorical questions",
        "English terms with non-redundant non-automated sortkeys"
      ],
      "glosses": [
        "That is very true; I agree (often with a gloomy or pessimistic tone)."
      ],
      "raw_glosses": [
        "(colloquial) That is very true; I agree (often with a gloomy or pessimistic tone)."
      ],
      "tags": [
        "colloquial"
      ]
    }
  ],
  "word": "ain't that the truth"
}