As the error message indicates, your method call Lerp expects different parameters from the ones you passed. It expects two Vector3 (a and b) and a float (t), because what this method does is interpolate between two vectors a and b at a time t.
You are passing the first parameter, for example, MCamera.position.x, which is the component x (a value float) vector position. You should probably come by MCamera.position directly (and the same goes for the parameter transform.position.x, that should be just transform.position).
If your interest is to interpolate only the value of x even, experiemente with Vector3(transform.position.x, 0, 0) (creates a new vector with only its value x, and with the value 0 for the components y and z).
P.S.: You should also make the last line be MCamera.position =
vetor instead of MCamera.position.x = vetor.
Hello. Welcome to SOPT. First of all, there is a tip for other questions in the future: do not post images with screenshots of your code. Post the code in textual form (properly formatted automatically by the system)! So anyone interested can just copy a snippet without having to type it all in manually.
– Luiz Vieira