RAM is short for Random Access Memory. In common parlance, RAM refers to system memory, the temporary storage area that holds all the data that the CPU is working on. All data that requires processing by the CPU and the results of the processing are first stored in the system memory.
RAM, per se, refers to the type of storage medium that allows any data stored within to be directly accessed without having to access the preceding data (the latter mode being called sequential access). System memory is volatile, which means that the stored data is lost when the device is powered down.