"Николаевичу" meaning in Russe

{
  "categories": [
    {
      "kind": "other",
      "name": "Formes de noms de famille en russe",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Russe",
      "orig": "russe",
      "parents": [],
      "source": "w"
    }
  ],
  "lang": "Russe",
  "lang_code": "ru",
  "pos": "name",
  "pos_title": "Forme de nom de famille",
  "senses": [
    {
      "glosses": [
        "Datif singulier de Николаевич."
      ],
      "id": "fr-Николаевичу-ru-name-cvw6Gdvt"
    }
  ],
  "tags": [
    "form-of",
    "surename"
  ],
  "word": "Николаевичу"
}

{
  "categories": [
    "Formes de noms de famille en russe",
    "russe"
  ],
  "lang": "Russe",
  "lang_code": "ru",
  "pos": "name",
  "pos_title": "Forme de nom de famille",
  "senses": [
    {
      "glosses": [
        "Datif singulier de Николаевич."
      ]
    }
  ],
  "tags": [
    "form-of",
    "surename"
  ],
  "word": "Николаевичу"
}