Pram is common in British English. I'm guessing you learned US English, which doesn't use it.

Though even in the UK I think it has a slightly old fashioned feel -- I feel like parents are more likely to have a pushchair than a pram.

Yes, as slang for ‘perambulator’, which is basically ‘stroller’

The word pram doesn't exist in American English, true, but you'll learn it anyway if you ever read Peter Pan.