The comment was referring to the Big-O Notation.
- O(1) means in constant time – independent of the number of items.
- O(N) means in proportion to the number of items.
- O(log N) means a time proportional to log(N)
Basically any ‘O’ notation means an operation will take time up to a maximum of k*f(N)
k is a constant multiplier
f() is a function that depends on N