RAM = Random access memory
It’s a form of data storage. “Random” means that the computer can access it from any point, as opposed to “sequential” access memory, which can only be read from start to finish (RAM is better than what I have now dubbed “SAM”. RAM is faster). The data is only active while it’s being used; if you turn the computer off, the data is deleted. RAM can be upgraded by changing the RAM chip inside the computer, or adding another chip, if the computer can hold more than one (replacing it is probably better).
Sorry about the tangent with nerd stuff...