He has no guts.

gut
 courage and fortitude; nerve; determination; stamina: 
Climbing that cliff takes a lot of guts.

take real guts
正真正銘のガッツを必要とする

You know, go with your guts, go with your instincts.
本能的に直観でやるだけさ。

He has no guts.
彼は根性がない。

not have the guts to talk to someone directly
直接［面と向かって］（人）に話し掛けるだけの勇気がない