good luck and godspeed什么意思?

楼上翻得对。从起源上讲godspeed中的speed是英语古文，是‘成功，繁荣昌盛’的意思。在现代英语里，speed是‘速度’。
The word Godspeed (which can also be written God-speed) is from Middle English. Godspeed is a nominalization of the phrase God speed (you), understanding which depends on two things: speed in this sense means 'to prosper; succeed', which is now archaic, but which is the original sense of the word; and the verb is subjunctive, expressing a wish, with the entire phrase meaning "may God cause you to succeed."
(Semantic parallels are such common expressions as God bless you or God forbid!)

祝愿你好运和平安.

万事如意.