这是一个感叹句的省略句.完整句子是：What a pleasure it is to see you again!
成分分析：形式主语 it；系词is；表语what a pleasure；真正主语to see you again.因此翻译大致是：再次看到你真开心（非感叹句：To see you again is a pleasure.It is a pleasure to see you again.）!