What does Cuando mean in spanish?

Cuando can either mean 'when' or 'since' depending on the condition of expression. An example of using cuando as 'when' is, "Cuando me llamas, te diré" (When you call me, I will tell you.) An example of using cuando as 'since' is "No sé por qué estás haciendo compras cuando no tienes dinero" (I don't know why you are shopping when/since you have no money).