AC to DC Bridge Rectifier DC Amperage Drop
It's a 2VA transformer and "VA" means volts x amps. If your output is 12V RMS then the current you can take is up to 167mA RMS. If you take any more current you are beginning to overload the transformer and it may get too warm and eventually burn-out.

With or without a full-wave (bridge) rectifier in place, the peak current obtainable without causing problems to your transformer is going to be about 1.414 times 167mA (236mA). This is playing a bit safe and assuming a resistive load. Given that your actual load may only draw short pulses of current, the peak level for that short duration could be double or triple this amount but, without knowing the circuit or the transformer in detail this is just an intuitive guess.