As you're using it, the term 'data' is referring to the maximum amount of information that can fit in the communications channel you're using.

Your personal data is largely limited by the fact that you're sharing that channel with many other people and your provider is only giving you a certain share of the maximum.

In terms of 'consuming', it would perhaps be better to say 'using'. If I run a bowling alley, I only have a limited number of shoes to rent and I only permit each customer to rent one pair of shoes. This limits the maximum number of customers I can have at one time, but I don't 'consume' the shoes - each customer returns the shoes after they're done.