What is the meaning when we put ./ and ../ while defining path for a file ?

Answer 1

A single dot means current path level, while double dots means previous path level.

So ./hello/ means to access "hello" directory in the current directory, while
../hello/ means to go on e directory up and then access "hello" directory

Answer 2

../ is used to go back to previous folder
./<folder_name> is used to access the folder having name folder_name