How can I extract specific data from a query to Notion?

My goal is to extract specific data, like "Nacionalidad", from a Notion connection, for using it in graphs or something like that.

I was able to connect the Notion database through a POST request and retrieve all the data that was in a table, but I can't find how to extract, for example, the 'Nationality' field.

I came across these two links (Retool Workflow Notion API Resource missing start_cursor field and Problem with querying Retool database table) but I'm not sure if they are related.