Confusion about Basic Structure Doctrine

Mere sahab, kya aapko pata hai ki Basic Structure Doctrine ka kya matlab hai? Main aajkal Constitutional Law class me stuck ho gaya hoon. Our professor ne yeh bataya ki yeh aadhaarit hai article 13 par, lekin phir bhi main samajh nahi paya ki yeh kya cheez hai. Voh keh rahe hain ki Basic Structure ka matlab hai ki Constitution me kuch bhi nahi badal sakte, chaahe woh judicial kiwajah se ho ya parliement ki. Lekin kya yeh sach hai? Kya hummein phir se kisi aur article ke andar se kuch badal sakte hain?

Main apne notes ko padha hoon, lekin abhi tak main samajh nahi paya.