Figuring out how to pronounce a new Spanish word is fairly easy, because there are consistent rules about how to pronounce each letter, and only two silent letters.
1. The letter H is always silent – the word is pronounced as if the h weren't there at all.
2. The letter U is sometimes silent in Spanish, but it has a purpose. When a U is preceded by G and followed by the soft vowels E or I, the letter U is silent.
For a U followed by E or I to be pronounced, you need a dieresis.