There are multiple reasons why you may need an assistant depending on your business goals. Maybe you don't have time or maybe you aren't clear on how to achieve your targets.
An assistant can complete your mundane tasks like email management or arranging meetings and travel, or they may be useful in helping you create your brand and gain followers. Your assistant might create and/or maintain your website. Your assistant may also help you with customer support by answering inquiries and directing clients.
This is a very personal decision but you will probably want to take into account what your specific needs are in relation to your budget. You should speak with your assistant over the phone initially to make sure that you click. It's very important to communicate clearly.