"била" meaning in Vieux slave

{
  "categories": [
    {
      "kind": "other",
      "name": "Formes de verbes en vieux slave",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Vieux slave",
      "orig": "vieux slave",
      "parents": [],
      "source": "w"
    }
  ],
  "lang": "Vieux slave",
  "lang_code": "cu",
  "pos": "verb",
  "pos_title": "Forme de verbe",
  "senses": [
    {
      "form_of": [
        {
          "word": "билъ"
        }
      ],
      "glosses": [
        "Féminin singulier de билъ."
      ],
      "id": "fr-била-cu-verb-3Jl9f~z-"
    },
    {
      "form_of": [
        {
          "word": "билъ"
        }
      ],
      "glosses": [
        "Neutre pluriel de билъ."
      ],
      "id": "fr-била-cu-verb-W-gsIbkd"
    },
    {
      "form_of": [
        {
          "word": "билъ"
        }
      ],
      "glosses": [
        "Masculin duel de билъ."
      ],
      "id": "fr-била-cu-verb-dfcoeE7c"
    }
  ],
  "tags": [
    "form-of"
  ],
  "word": "била"
}

{
  "categories": [
    "Formes de verbes en vieux slave",
    "vieux slave"
  ],
  "lang": "Vieux slave",
  "lang_code": "cu",
  "pos": "verb",
  "pos_title": "Forme de verbe",
  "senses": [
    {
      "form_of": [
        {
          "word": "билъ"
        }
      ],
      "glosses": [
        "Féminin singulier de билъ."
      ]
    },
    {
      "form_of": [
        {
          "word": "билъ"
        }
      ],
      "glosses": [
        "Neutre pluriel de билъ."
      ]
    },
    {
      "form_of": [
        {
          "word": "билъ"
        }
      ],
      "glosses": [
        "Masculin duel de билъ."
      ]
    }
  ],
  "tags": [
    "form-of"
  ],
  "word": "била"
}