A pram is a stroller or baby carriage, a device with wheels that can be easily pushed. Some fussy babies are soothed by a long stroll in a pram.
The typical pram has four wheels and a handle. The baby or toddler can sit or lie down in the pram while being wheeled along the street. While pram is a British term — it's more likely to be called a stroller in the US — most parents, babysitters, and nannies will know what you mean if you use the word. Pram is short for perambulator, "one who walks or perambulates," which gained the meaning "baby carriage" in the 1850s.