"一头长发" 用英语可以说作 "a head of long hair"。
其中，"head" 是指 "头" 的意思，而 "of" 是用来连接名词的介词，表示所属关系。而 "long hair" 则是指 "长发"。
一些英文例句及其中文翻译如下：
She brushed her head of long hair. (她梳理了她一头长发。)
He grew a head of long hair for his role in the play. (他为了剧中的角色而长出了一头长发。)
She had a beautiful head of long hair that reached her waist. (她有一头美丽的长发，可以抵达腰部。)