beginning-of-line-text is an interactive compiled Lisp function in `indent.el'.

(beginning-of-line-text &optional N)

Move to the beginning of the text on this line.
With optional argument, move forward N-1 lines first.
From the beginning of the line, moves past the left-margin indentation, the
fill-prefix, and any indentation used for centering or right-justifying the
line, but does not move past any whitespace that was explicitly inserted
(such as a tab used to indent the first line of a paragraph).