he doubled the lead in the second half when he converted Lan

he converted Landon Donovan's pass from close range
from close range是修饰pass的,“短传”的意思；
这句省略了一部分,完整的应该是he converted Landon Donovan's pass from close range into goal（射门）.
字面意思是“他将由 Landon Donovan短传过来的球转换成射门球”,意思就射门了!
其实也就是Landon Donovan用短传助攻了他一球.

convert是转换的意思，这个句子里面说的是他把Landon Donovan的传球转化成了近距离的射门