A website's accessibility isn't obvious by looking at it. This demo site for Lulu's Lollipops looks like it works but has lots of accessibility errors. There are a number of errors on the site, but let's experience one; try using the Tab key on your keyboard to access the Our Lollipops menu. You can't get to the button, which means that users who don't use a mouse can't get to that page either.
This is called manual testing. You can manually test your own pages by making sure you can interact with all components of the page using the keyboard. (Using the Enter key should select the item.)