"bollo postale" meaning in Italian

{
  "forms": [
    {
      "form": "bolli postali",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "m"
      },
      "expansion": "bollo postale m (plural bolli postali)",
      "name": "it-noun"
    }
  ],
  "lang": "Italian",
  "lang_code": "it",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Italian entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "postmark"
      ],
      "id": "en-bollo_postale-it-noun-QKn4Xvaj",
      "links": [
        [
          "postmark",
          "postmark"
        ]
      ],
      "tags": [
        "masculine"
      ]
    }
  ],
  "word": "bollo postale"
}

{
  "forms": [
    {
      "form": "bolli postali",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "m"
      },
      "expansion": "bollo postale m (plural bolli postali)",
      "name": "it-noun"
    }
  ],
  "lang": "Italian",
  "lang_code": "it",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Italian countable nouns",
        "Italian entries with incorrect language header",
        "Italian lemmas",
        "Italian masculine nouns",
        "Italian multiword terms",
        "Italian nouns",
        "Italian nouns with red links in their headword lines"
      ],
      "glosses": [
        "postmark"
      ],
      "links": [
        [
          "postmark",
          "postmark"
        ]
      ],
      "tags": [
        "masculine"
      ]
    }
  ],
  "word": "bollo postale"
}