I assume it's the word "bespoke" which you don't understand?
That isn't a Java term at all. It's an English word (of which the American equivalent is "custom"), and it simply means "made for a specific person or purpose". For example you can ask somebody to make a suit for you, in which case it would be a "bespoke suit". Or you could ask for somebody to write a Java application for your specific need, in which case it would be a "bespoke application".