Confused about Section 91 of Indian Evidence Act

Main to pagal ho raha hun, abhi 2:45 am ka ho raha hai, lekin ek baat toh khatam karne ki zaroorat hai. Main to 3 din mein exam mein ja raha hun, lekin Section 91 of Indian Evidence Act ki wajah se mujhe thik se koi samajh nahi hai. Main to socha tha ki ye section keval witness statement ko reject karne ki power deta hai, lekin abhi to mujhe lagta hai ki ismein kuch aur bhi hai. Main to bahut pareshan hun, kya main aisa hi socha tha, ya phir main galat hai... Plz koi bhai ka help kare, kya Section 91 ke baare mein main kuch galat socha tha?