"a fe" meaning in Spanish

{
  "head_templates": [
    {
      "args": {},
      "expansion": "a fe",
      "name": "es-adv"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Spanish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "bold_english_offsets": [
            [
              65,
              73
            ]
          ],
          "bold_text_offsets": [
            [
              56,
              60
            ]
          ],
          "english": "It's been about three nights I haven't slept -she replied-. It's actually because there's been little to do...",
          "ref": "1877, Benito Pérez Galdós, Gloria:",
          "text": "-Como que hace tres noches que no duermo -repuso ella-. A fe que hay poco que hacer...",
          "type": "quote"
        }
      ],
      "glosses": [
        "actually; truth be told"
      ],
      "id": "en-a_fe-es-adv-FaF24a9k",
      "links": [
        [
          "actually",
          "actually"
        ],
        [
          "truth be told",
          "truth be told"
        ]
      ],
      "raw_glosses": [
        "(idiomatic) actually; truth be told"
      ],
      "tags": [
        "idiomatic"
      ]
    }
  ],
  "word": "a fe"
}

{
  "head_templates": [
    {
      "args": {},
      "expansion": "a fe",
      "name": "es-adv"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        "Pages with 1 entry",
        "Pages with entries",
        "Spanish adverbs",
        "Spanish entries with incorrect language header",
        "Spanish idioms",
        "Spanish lemmas",
        "Spanish multiword terms",
        "Spanish terms with quotations"
      ],
      "examples": [
        {
          "bold_english_offsets": [
            [
              65,
              73
            ]
          ],
          "bold_text_offsets": [
            [
              56,
              60
            ]
          ],
          "english": "It's been about three nights I haven't slept -she replied-. It's actually because there's been little to do...",
          "ref": "1877, Benito Pérez Galdós, Gloria:",
          "text": "-Como que hace tres noches que no duermo -repuso ella-. A fe que hay poco que hacer...",
          "type": "quote"
        }
      ],
      "glosses": [
        "actually; truth be told"
      ],
      "links": [
        [
          "actually",
          "actually"
        ],
        [
          "truth be told",
          "truth be told"
        ]
      ],
      "raw_glosses": [
        "(idiomatic) actually; truth be told"
      ],
      "tags": [
        "idiomatic"
      ]
    }
  ],
  "word": "a fe"
}