Radical 人
4 strokes
barb
(120a) + a drop 丶 (22a) + person 人 (12) = using 以
The meaning of this character is hard to pin down in English: depending on how it is used, it could be translated by words such as “using”, “by means of ”, “according to”, “in order to”, etc. It is also used in “positional” compounds such as the two given here.
以前 (90) yǐqián before; a while ago
以外 (71) yǐwài apart from, except

Harry puts a drop of colored wax on the barb of his fish-hook, using the bright colors of the wax to attract the fish. / Teddy tries it too, and catches an eel.

This is used in the following character and we will see it again later in the book. Note that the downward vertical line and the hook together count as only one stroke.