What is the use of pre-computed points in ECC? I am trying to understand the use of pre-computed points in ECC for ECC signature, verification, key generation, and so on. After searching on the internet, I understand that pre-computed points aid faster execution. However, I am unable to get the complete picture. Can someone help with an example? Also, once the pre-computed points are calculated, are these secrets?
Can someone help with an example?

Ok, here's a simple example; suppose we precompute a table that contained all the points of the form $(a \cdot 256^b) G$, for $0 &lt; a &lt; 256$ and where $b$ be within the scalar we intend to support.
For example, the table (if we support 2 byte scalars) would contain the points $\text{0x01}G, \text{0x02}G, …,\text{0xff}G, \text{0x0100}G, \text{0x0200}G, …, \text{0xff00}G$
Then, to compute the value $0x1234G$, we would look up $0x1200G$ in our table and the value $34G$, and then add them $0x1200G + 0x34G = 0x1234G$; we just computed the point multiplication with a single addition (and some table lookups); using a table without precomputation would use at least 13 point additions/doublings.
It should be obvious how this table can be extended to support longer scalars; if we support 32-byte scalars (appropriate for 256-bit curves), we can do any point multiplication using 31 additions (and a large table).
There are a number of ways to build the table (including methods with much smaller tables and not that much more computation required); I picked this example solely because it was easy to understand.

Also, once the pre-computed points are calculated, are these secrets?

Only if the base point is secret.  As this is most commonly used with the public curve generator point, there is usually no need.
Also, the tables/algorithms can be set up to run in constant time; however that is rather trickier.