"How many visits (or visitors) can my website get?" is basically the golden question of any website service, which can only be answered through trial and error.
The answer depends on what those visits look like, for example: how many pages are viewed, how long do they last, how well are they spread out over time. Your website also matters, if your website has a lot of images, stylesheets and scripts, that will increase your hits and bandwidth usage. If your PHP code is complex, it will increase CPU and memory usage.
The next time your account is suspended, click the knowledge base link in the client area to learn more about the limit you've reached and try to follow it's recommendations. If you're having trouble applying the tips and still get suspended regularly, please consider moving your website to premium hosting.