This is an Irish colloquial expression that means something is easy to do or simple to achieve: "That exam was a doddle. A child could have passed it." This is an informal expression usually used in social contexts.

1. The English test was a doddle. I'm sure I passed.
2. I just started using my new laptop. The setup was a doddle.

1. This project is a doddle, I'll have it finished in a couple of hours.
2. The new software is a doddle to use, the tutorials are excellent.