If someone likes your Facebook business page then they are automatically added to follow the page. (You can only follow a page once you have liked it) The follow is set to default.
They then have the option to unfollow the page or see first. This means that "likers" can unfollow so they will not see your posts in their news feed. They can also set to "see first" which means your posts will be prioritsed in their feed. I wouldn't sweat it though because most people who follow a page don't bother using these settings.
So to clarify, by default, they will see your posts.