Compound nouns are two word combinations that create a phrase with a new meaning.
For instance, “bus” is a a large motor vehicle for carrying passengers .  “Stop” means to end.  When used together, the meaning changes to a place to get on or off of the bus.
Stress is important in pronouncing compound nouns, as it distinguishes it as a new phrase, not two separate words.  To say a compound noun correctly, link the words, basically, say the words together as if they are one word.  Do not pause between the words.  The word stress falls on word number one.  That means that the stressed word is pronounced louder, higher in pitch, and with a longer vowel.