Random Number In R Value , what is it actually, is it the same as Nonce in the blocks
The nonce in a signature is different from the nonce used in the block header. These are unrelated to each other. They only share a name because the term nonce is a generic word that means &quot;a number used only once.&quot;
A signature is composed of two numbers: R and s. R is the X coordinate of a random nonce k multiplied by the generator point G. It is the result of elliptic curve scalar multiplication with a point. k is a scalar, which means it is just a random integer modulo the n, the order of  G.
The nonce k must be kept private. If it is known, then anyone can compute the private key used in the signature. Additionally, reusing the same k (which results in R being the same) with the same private key will allow the private key to be computed.