Because they face the sun and moon at different times. The time zones were created due to the sun and moon being visible in different parts of the Earth at different times
It is because different places have different latitudes and longitudes with which time can be calculated. There can be different time in one country also if the latitude and longitude changes, so...
First, regard the Sun as fixed in place. The Earth is a sphere, and rotates on its axis once per 24 hours. Thus the Sun is at its highest once per day at your location, and we consider it to be...
Picture the earth as being a basket ball and the sun a flashlight. Shine the flashlight on the basket ball and you will see that the light only shines on one side. As the earth spins on its own axis...