Q.how to keep terrace garden’s temperature in check in summer
I live in India, M.P. and sometimes in summer temperature reached 45-degree Celsius, I have started making terrace garden in December 2018 so, I am fairly new in this gardening thing and I am worried about summers when temperatures are harsh so i ordered 50% shade cloth from Amazon and I am still worried how to keep my plants moist and protect from high temperatures such as 45-degree celsius.

The shade cloth is vital. Also to consider is a fan or multiple fans, and a garden mist-fog machine.
https://www.alibaba.com/product-detail/Automatic-plant-mister-small-size-cooling_60610713756.html?spm=a2700.7724857.normalList.11.54431f11HGYCxH&s=p
If your garden planting areas can accommodate trees, then shade trees are another possibility. It is considerably cooler underneath the foliar canopy of a neem tree.