[
    {
        "company": "Google",
        "location": "USA",
        "email": null
    },
    {
        "company": "Microsoft",
        "location": "USA",
        "email": "mail@mail.com"
    },
    {
        "company": "Google",
        "location": "NLD",
        "email": "mail@mail.com"
    }
]

[x] Google (2)
[ ] Microsoft (1)
// other function call
[ ] mail@mail.com (2)

function filterArr(data, key) {

    data.forEach(element => {

        let countedData = data.filter((el) => {
            return el[key] == element[key]
        }).length;
// console.log(element[key] + ": " + countedData);
    });

    data = data.filter((item, index, self) => self.findIndex( t => t[key] === item[key] && item[key] != null) === index )
// console.log(data)
    return data;
}

filterArr(data, "company");