"We are going to take many photos" 或 "We are going to take a lot of photos" 都可以用来表示将要拍很多照片的意思。
"We are going to take many photos" 中的 "many" 是形容词，表示很多的意思。
"We are going to take a lot of photos" 中的 "a lot of" 是副词短语，也表示很多的意思。
例句：
We are going to take many photos at the park.
I can't wait to take a lot of photos on our vacation.
I want to take many photos of my family together.
We are going to take a lot of photos at the concert tonight.
Let's take many photos at the beach before we leave.