To find the coordinates of point \( B' \) after the translation, we start with the original coordinates of point \( B \), which are given as \( B = (-1, 4) \).
The translation involves moving the point:
- 2 units to the left, which means we subtract 2 from the x-coordinate.
- 4 units down, which means we subtract 4 from the y-coordinate.
Applying the translation to the coordinates of \( B \):
- New x-coordinate: \( -1 - 2 = -3 \)
- New y-coordinate: \( 4 - 4 = 0 \)
Therefore, the coordinates of \( B' \) after the translation are:
\[ B' = (-3, 0) \]