In most cases in the English language the letter h is pronounced as an aspiration.
In some cases this letter is silent, no matter if it is at the beginning, in the middle or at the end of a word.
Words with silent h:
- hour, honor, honest;
- vehicle, shepherd, exhausted;
- messiah, fish, church.
There are no definite rules to help you distinguish whether the h is pronounced or not. The exceptions should be learned by heart.