A trillion is a very large number, bigger than a billion.
You might hear people talk about trillions when they discuss money - for example, the government budget or national debt. In these cases, it means an extremely large amount of money, like one followed by 12 zeros: 1,000,000,000,000. This can sound overwhelming and hard to imagine.
(US, modern British, Australia, short scale) A million (times a) million: 1 followed by twelve zeros, 10¹².
