Buyer personas are fictional, generalized representations of your ideal customers and help you understand who to target.
Buyer personas help you understand your customers (and prospective customers) better and make it easier for you to tailor content to the specific needs, behaviors, and concerns of different groups.
At the most basic level, personas allow you to personalize or target your marketing for different segments of your audience. For example, instead of sending the same lead nurturing emails to everyone in your database, you can segment by buyer persona and tailor your messaging according to what you know about those different personas.