The noun "jam" can be both countable and uncountable.
Meaning: sweet food that's made from fruit and usually spread on bread or toast
Example sentence: Would you like some strawberry jam with your toast, madam?
Meaning: many vehicles stuck together in traffic, or a difficult situation
Example sentence: Brad said he was late because he was caught in a traffic jam.
Test your understanding:
- We couldn't get to the supermaket in time because of the traffic jam.
- We haven't got jam because we couldn't get to the supermaket in time.