First things first, the color of the plant leaves are mainly due to chemical pigments inside their cell. The green color is from the chlorphyll, red is from anthocyanin, orange is from carotenoids and yellow is from xanthophyll. Now, leaves change colors when fall is near because during fall, leaves stop their food making process (called photosynthesis) and prepare for harsher conditions( winter or rainy days– resultsh to low sunlight) thus, chlorophylls are broken down and red, yellow, and orange pigments become more visible. Spring and summer are the seasons where leaves start to produce massive amount of chlorophylls because during these seasons sunlight is abundant, and days are longer, we all know that sunlight is needed for the process of photosynthesis, it is also during these seasons that the massive amount of chlorphylls mask the red, orange, and yellow pigments of the leaves.

I hope this helps, I've learned this in my Botany haha