This is the 5573rd most frequent Korean word.
묶어야
"Must tie" or "must bind."
In this sentence, "묶어야" refers to the necessity of tying.
신발끈을 단단히 묶어야 다치지 않아요.
You need to tie your shoelaces tightly to avoid injury.
In this context, "묶어야" implies combining objects to make them secure.
두 개의 줄을 하나로 묶어야 강하게 고정됩니다.
You need to tie two ropes together to secure them strongly.
Here, "묶어야" metaphorically means to 'connect' or 'bind' memories through photos.