He only needs to say so and I'll do it.
We only have to go there and we'll know.
You only need to change the socket that it will work fine.

Basta que lo diga y lo hacemos.
= It is enough that he says so and we'll do it.
Basta que vayamos, y lo vamos a saber.
= It is enough that we go there and we'll know.
Basta que cambiés el enchufe para que funcione.
= It enough that you change the socket that it will work fine.