It's a joke. Pomodoro means tomato.

But it's also not a joke.

Pomodoro timers are designed to increase productivity. But once of the things that many people who try to increase their productivity discover is that they sink so much time into these tools that they are less productive. Because the underlying procrastination isn't solved, and these tools are a wonderful outlet for procrastination because it feels productive.

That may indeed not be OP's problem, but anyone looking at this saying "I need to be more productive, I should make one of these" would be better off with the tomato.

I’m pretty sure that’s the origin of the term