Here's how we can tell:
* Short vowels are usually pronounced quickly and have a short, sharp sound.
* Long vowels are usually pronounced with a longer, drawn-out sound.
In "hospitality," the following vowels are short:
* o in "hos" is pronounced with a short "o" sound, similar to the "o" in "hot".
* i in "pi" is pronounced with a short "i" sound, similar to the "i" in "pit".
The other vowels in the word have longer sounds:
* a in "tality" is pronounced with a long "a" sound, similar to the "a" in "ate".
Therefore, the word "hospitality" contains two short vowels ("o" and "i") and two long vowels ("a" and "i").