"yesterday but one" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "yesterday",
        "3": "but",
        "4": "one",
        "t2": "except for"
      },
      "expansion": "yesterday + but (“except for”) + one",
      "name": "compound"
    }
  ],
  "etymology_text": "yesterday + but (“except for”) + one https://www.observer.ug/lifestyle/42-entertainment/44856-kataaha-has-to-sort-out-the-cracks-in-english",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "yesterday but one (not comparable)",
      "name": "en-adv"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1917, William Hope Hodgson, The Mystery of Captain Chappel",
          "text": "\"Yesterday but one I located a number of them twisted matches in the floor sweepings of the Slade Arms; an' all that evenin' I sat there, watchin' the different men that came in an' had a drink an' a smoke; but I couldn't get onto no one. …\"",
          "type": "quotation"
        },
        {
          "ref": "2020 April 21, “How Uganda’s history of epidemics has prepared it for COVID-19” (4:49 from the start), in PBS NewsHour, Michael Baleke (actor), WETA-TV, via Public Broadcasting Service",
          "text": "Yesterday but one [the day before yesterday], I bought a kilo of beans at 4,000 [shillings]. Yesterday, I came back and it was 5,000.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Day before yesterday."
      ],
      "id": "en-yesterday_but_one-en-adv-Yh4V-Mk6",
      "links": [
        [
          "Day before yesterday",
          "day before yesterday"
        ]
      ],
      "raw_glosses": [
        "(dialectal) Day before yesterday."
      ],
      "tags": [
        "dialectal",
        "not-comparable"
      ]
    }
  ],
  "word": "yesterday but one"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "yesterday",
        "3": "but",
        "4": "one",
        "t2": "except for"
      },
      "expansion": "yesterday + but (“except for”) + one",
      "name": "compound"
    }
  ],
  "etymology_text": "yesterday + but (“except for”) + one https://www.observer.ug/lifestyle/42-entertainment/44856-kataaha-has-to-sort-out-the-cracks-in-english",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "yesterday but one (not comparable)",
      "name": "en-adv"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        "English adverbs",
        "English compound terms",
        "English dialectal terms",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English terms with quotations",
        "English uncomparable adverbs"
      ],
      "examples": [
        {
          "ref": "1917, William Hope Hodgson, The Mystery of Captain Chappel",
          "text": "\"Yesterday but one I located a number of them twisted matches in the floor sweepings of the Slade Arms; an' all that evenin' I sat there, watchin' the different men that came in an' had a drink an' a smoke; but I couldn't get onto no one. …\"",
          "type": "quotation"
        },
        {
          "ref": "2020 April 21, “How Uganda’s history of epidemics has prepared it for COVID-19” (4:49 from the start), in PBS NewsHour, Michael Baleke (actor), WETA-TV, via Public Broadcasting Service",
          "text": "Yesterday but one [the day before yesterday], I bought a kilo of beans at 4,000 [shillings]. Yesterday, I came back and it was 5,000.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Day before yesterday."
      ],
      "links": [
        [
          "Day before yesterday",
          "day before yesterday"
        ]
      ],
      "raw_glosses": [
        "(dialectal) Day before yesterday."
      ],
      "tags": [
        "dialectal",
        "not-comparable"
      ]
    }
  ],
  "word": "yesterday but one"
}