You might not have noticed from just standing the Earth's surface but the whole Earth tilts over slightly.
When looking at a globe in school or at home, you can see that the line cutting through the center of the Earth between north and south poles isn't vertical.
It's actually tilting over by about 23.5 degrees.
In our summer the North Pole is pointing towards the Sun, therefore the Sun rises and sets roughly from due east to due west.
In winter months, the Earth has traveled to the other side of the Sun causing the North Pole to point away from the Sun.
This means that the Sun rises and sets more towards the southeast and southwest.
For example, think back to how high in the sky the sun was during the summer and compare this to where the sun is during the winter.
In the winter the Sun will be much lower down towards the horizon, causing there to be less time and distance for it to travel between horizons.
Therefore the sun rises later and sets earlier in the winter compared to the summer, meaning there's less daylight in the winter.