What does "sample mean" mean?

Given a random sample mathbf x₁,…, mathbf x_N from an n-dimensional random variable mathbf X, a mean defined as

Sample mean

noun

noun ·Rare ·Advanced level

Noun

1
Given a random sample mathbf x₁,…, mathbf x_N from an n-dimensional random variable mathbf X, a mean defined as
"mathbf ̄x=1/N∑ₖ₌₁ᴺ mathbf xₖ."