Functions - Which possible options for the parameters?

Within the Function Calling Docu we have a parameter object.

However: I couldn’t find any information about the possible properties etc. and for what they are responsible?

Also the required field. Can someone point me into the right direction?

    "type": "function",
    "function": {
      "name": "getCurrentWeather",
      "description": "Get the weather in location",
      "parameters": {
        "type": "object",
        "properties": {
          "location": {"type": "string", "description": "The city and state e.g. San Francisco, CA"},
          "unit": {"type": "string", "enum": ["c", "f"]}
        "required": ["location"]