Recruitment companies and departments often try to be clever when advertising a vacancy with a request like this, to go along with your CV/résumé. The truth is, though, they don’t actually mean it. What they really mean is, “write a covering letter explaining what you will contribute to our company.”
As long as you realise this, you can use this cover letter to gain the edge on other candidates who take that request literally. And what happens to them? Their letters come across as boastful, “me-me-me” documents that unwittingly make them look like they’re totally up themselves and only regard the job concerned as an opportunity to advance themselves. and that’s hardly what today’s employers are looking for.