What's the meaning of cash?

[Felix Torres]

Hi Everyone,

I always hear about cash transaction, but also hear about investment products associated with them. 

Can someone explain what the meaning of "cash" means in real estate? 

This question might sound obvious, but  this is for investors  (including my self) who legit think they need to raise all that cash on their own or in general to compete with others in the market.

Thank you,

Felix