Ruby question on splitting and indices

Was hoping someone could help explain the the logic behind the code below. I understand most it of other than when concatenating part[0] into initials. We split the string into an array, in this case (“Kelvin Bridges”) into [“Kelvin”, “Bridges”]. Isn’t “Bridges” technically at an index of 1? Or does |part| evaluate “Kelvin” and "Bridges as separate arrays?

def to_initials(name)
      parts = name.split(" ")
      initials = ""
      parts.each { |part| initials += part[0] }
      return initials
end

puts to_initials("Kelvin Bridges")      # => "KB"

parts is ["Kelvin", "Bridges"]

So that’s a list with two items.

So for each item of parts, concatenate the first character (the character at index 0) to initials