Something that's digestible can be easily eaten or swallowed and broken down in your body. You might have trouble digesting spicy food.
When we talk about something being digestible, it usually means it's easy to understand. Not just food! For example, if someone explains a complicated topic in simple terms, you could say the explanation was very digestible. If you watch a documentary with subtitles, that can make it more digestible too - easier to follow.
Capable of being digested.
